Operation Grapple was the name of four series of British nuclear
weapons tests of early atomic bombs and hydrogen bombs carried out in
1957 and 1958 at
Malden Island and Christmas Island in the Pacific
Ocean as part of the British hydrogen bomb programme. Nine nuclear
explosions were initiated, culminating in the United Kingdom becoming
the third recognised possessor of thermonuclear weapons, and the
restoration of the nuclear
Special Relationship with the United States
with the 1958 US-UK Mutual Defence Agreement.
During the Second World War, Britain had a nuclear weapons project,
codenamed Tube Alloys, which was merged with the American Manhattan
Project in August 1943. Many of Britain's top scientists participated
in the British contribution to the Manhattan Project. After the war,
fearing that Britain would lose its great power status, the British
government resumed the atomic bomb development effort, now codenamed
High Explosive Research. The successful test of an atomic bomb in
Operation Hurricane in October 1952 represented an extraordinary
scientific and technological achievement, but Britain was still
several years behind the United States in nuclear weapons technology.
In July 1954, Cabinet decided to develop the hydrogen bomb.
United Kingdom Atomic Energy Authority
United Kingdom Atomic Energy Authority Atomic Weapons
Aldermaston produced three designs: Orange Herald, a
large boosted fission weapon; Green Bamboo, an interim thermonuclear
design; and Green Granite, a true thermonuclear weapon. The first test
series consisted of three tests in May and June 1957. In the first,
Grapple 1, a version of Green Granite known as Short Granite was
dropped from a
Vickers Valiant bomber flown by Wing Commander Kenneth
Hubbard. The bomb's yield was estimated at 300 kilotonnes of TNT
(1,300 TJ), far below its designed capability. Despite its
failure, the test was hailed as a successful thermonuclear explosion,
and the government did not confirm or deny reports that the UK had
become a third thermonuclear power. The second test was Grapple 2, of
Orange Herald. Its 720-to-800-kilotonne-of-TNT (3,000 to
3,300 TJ) yield made it technically a megaton weapon. It was the
largest ever achieved by a single stage device. Grapple 3 tested
Purple Granite, a Short Granite with some fixes. Its yield was a very
disappointing 300 kilotonnes of TNT (1,300 TJ).
A second test series was required. This consisted of a single test,
known as Grapple X, in November 1957. This time the yield of 1.8
megatonnes of TNT (7.5 PJ) exceeded expectations. This was a true
hydrogen bomb, but most of the yield came from nuclear fission rather
than nuclear fusion. In a third series with a single test, known as
Grapple Y, in April 1958, another design was tested. With an explosive
yield of about 3 megatonnes of TNT (13 PJ), it remains the
largest British nuclear weapon ever tested. The design of Grapple Y
was notably successful because much of its yield came from its
thermonuclear reaction instead of fission of a heavy uranium-238
tamper, making it a true hydrogen bomb, and because its yield had been
closely predicted—indicating that its designers understood what they
were doing. A final series of four tests in August and September 1958,
known as Grapple Z, tested techniques for boosting and making bombs
immune to predetonation caused by nearby nuclear explosions. Two of
these tests were detonations from balloons; another was a blind radar
test drop. A moratorium on testing came into effect in October 1958,
and Britain never resumed atmospheric testing.
4 Grapple series
5 Grapple X
6 Grapple Y
7 Grapple Z series
8.1 Cooperation with the United States
8.2 Health effects
8.3 Operation Dominic
12 External links
Main article: British hydrogen bomb programme
During the early part of the Second World War, Britain had a nuclear
weapons project, codenamed Tube Alloys. At the Quebec Conference in
August 1943, the Prime Minister of the United Kingdom, Winston
Churchill and the President of the United States, Franklin Roosevelt,
signed the Quebec Agreement, which merged
Tube Alloys with the
Manhattan Project to create a combined British, American and
Canadian project. The September 1944 Hyde Park Agreement
extended both commercial and military cooperation into the post-war
period. Many of Britain's top scientists participated in the
British contribution to the Manhattan Project.
The British government had trusted that America would continue to
share nuclear technology, which it considered to be a joint
discovery. On 16 November 1945, Truman and Attlee signed a new
agreement that replaced the Quebec Agreement's requirement for "mutual
consent" before using nuclear weapons with one for "prior
consultation", and there was to be "full and effective cooperation in
the field of atomic energy", but this was only "in the field of basic
scientific research". The United States Atomic Energy Act of 1946
(McMahon Act) ended technical cooperation. The revelation of a
Canadian spy ring that included British physicist
Alan Nunn May while
the bill was being prepared caused the
United States Congress
United States Congress to add
the death penalty for sharing "restricted data" with foreign
nations. Efforts to rebuild the nuclear
Special Relationship with
the United States over the following decade were dogged by repeated
spy scandals, including the arrest of
Klaus Fuchs in 1950, and the
Guy Burgess and Donald Maclean in 1951. Fearing a
resurgence of American isolationism and Britain losing its great power
status, the British government restarted its own development
effort, now codenamed High Explosive Research.
The successful test of an atomic bomb in
Operation Hurricane in
October 1952 represented an extraordinary scientific and technological
achievement. Britain became the world's third nuclear power,
reaffirming the country's status as a great power, but hopes that the
United States would be sufficiently impressed to restore the Special
Relationship were soon dashed. In November 1952, the United States
conducted Ivy Mike, the first successful test of a true thermonuclear
device or hydrogen bomb. Britain was therefore still several years
behind in nuclear weapons technology. The Defence Policy
Committee, chaired by Churchill and consisting of the senior Cabinet
members, considered the political and strategic implications in June
1954, and concluded that "we must maintain and strengthen our position
as a world power so that Her Majesty's Government can exercise a
powerful influence in the counsels of the world." In July 1954,
Cabinet agreed to proceed with the development of thermonuclear
United Kingdom Atomic Energy Authority
United Kingdom Atomic Energy Authority Atomic Weapons
Aldermaston in Berkshire was directed by William
Penney, with William Cook as his deputy. The scientists at
Aldermaston did not know how to build a hydrogen bomb, but
produced three designs: Orange Herald, a large boosted fission weapon
in which the fission yield was increased ("boosted") though the
addition of lithium-6 deuteride; Green Bamboo, an interim
thermonuclear design in which fusion occurred in layers of lithium-6
deuteride that alternated with layers of uranium-235; and Green
Granite, a true thermonuclear design in which the thermonuclear fuel
was separate and the majority of the yield came from thermonuclear
burning. The British bomb designers used the terms "Tom" and
"Dick" for the bomb's primary and secondary stages respectively. The
Tom would be a fission bomb. It would produce radiation to implode the
Dick. Implicit in the creation of a hydrogen bomb was that it
would be tested. Eden, who replaced Churchill as prime minister after
the latter's retirement on 5 April 1955, gave a radio broadcast in
which he declared: "You cannot prove a bomb until it has exploded.
Nobody can know whether it is effective or not until it has been
Testing of the boosted designs was carried out in the Operation Mosaic
tests in the Monte Bello Islands in May and June 1956. This was a
sensitive matter; there was an agreement with Australia that no
thermonuclear testing would be carried out there. The Australian
Minister for Supply, Howard Beale, responding to rumours reported in
the newspapers, asserted that "the Federal Government has no
intention of allowing any hydrogen bomb tests to take place in
Australia. Nor has it any intention of allowing any experiments
connected with hydrogen bomb tests to take place here." Since the
tests were connected with hydrogen bomb development, this prompted
Eden to cable the Prime Minister of Australia, Robert Menzies,
detailing the nature and purpose of the tests. He promised that the
yield of the second, larger test would not exceed two and a half times
that of the
Operation Hurricane test, which was 25 kilotonnes of
TNT (100 TJ). Menzies cabled his approval of the tests on 20 June
1955. In the event, the yield of the second test was 60 kilotonnes
of TNT (250 TJ), which was larger than the 50 kilotonnes
of TNT (210 TJ) limit on tests in Australia.
The survey ship HMNZS Lachlan
Another test site was therefore required. For safety and security
reasons, in the light of the Lucky Dragon incident, in which the crew
of a Japanese fishing boat were exposed to radioactive fallout from
Castle Bravo nuclear test, a large site remote from
population centres was required. Various islands in the South Pacific
and Southern Oceans were considered, along with Antarctica. The
Admiralty suggested the Antipodes Islands, which are about 860
kilometres (530 mi) southeast of New Zealand. In May 1955,
the Minister for Defence, Selwyn Lloyd, concluded that the Kermadec
Islands, which lie about 1,000 kilometres (620 mi) northeast
of New Zealand, would be suitable.
They were part of New Zealand, so Eden wrote to the Prime Minister of
New Zealand, Sidney Holland, to ask for permission to use the islands.
Holland refused, fearing an adverse public reaction in the upcoming
1957 general election in New Zealand. Despite reassurances and
pressure from the British government, Holland remained firm. The
search for a location continued, with
Malden Island and McKean Island
being considered. These were uninhabited islands claimed by both
Britain and the United States. The former island became the
frontrunner. Three Avro Shackletons from No 240 Squadron were sent to
conduct an aerial reconnaissance from Canton Island. It too was
claimed by both the United States and Britain, and was jointly
administered, so the Americans had to be informed. Holland agreed to
send the survey ship HMNZS Lachlan to conduct a maritime
Christmas Island was chosen as a base. It too was claimed by both
Britain and the United States. Lying just north of the equator, it
was a tropical island, largely covered in grass, scrub and coconut
plantations. Temperatures are high, averaging 88 °F
(31 °C) during the day and 78 °F (26 °C) at night,
and humidity is very high, usually around 98 per cent. It lay
1,450 miles (2,330 km) from Tahiti, 1,335 miles (2,148 km)
from Honolulu, 3,250 miles (5,230 km) from San Francisco and
4,000 miles (6,400 km) from Sydney. Its remotest would dominate
the logistic preparations for Operation Grapple. It had no
indigenous population, but about 260 Gilbertese civilians lived on the
island, in a village near Port London. They came from the Gilbert
and Ellice Islands, and worked the coconut plantations to produce
copra. While most only stayed for a year or two, some had been on the
island for a decade or more.
South Pacific Air Lines (SPAL) had been granted permission by the
United States and British governments to operate a flying boat service
from Christmas Island.
Patrick Dean asked the British Ambassador to
the United States, Sir
Roger Makins to sound out the U.S. government
about terminating the contract. Makins reported in March 1956 that
Admiral Arthur W. Radford, the Chairman of the Joint Chiefs of Staff,
was willing to help so long as the dormant American claim to the
island was not prejudiced. The lease on the island facilities,
including the airfield and the port, had been granted to SPAL with a
clause in the contract that said it could be terminated if there was a
military necessity to do so. The Americans proposed that the British
tell SPAL that they were establishing an airbase on the island, and
that the United States would support this so long as SPAL was paid
fair compensation. An official letter was sent to the president of
SPAL on 1 May 1956, withdrawing the permit to operate from Christmas
Island, regretting any inconvenience, and offering to consider
Royal Engineers assemble huts on Christmas Island
The test series was given the secret codename Operation Grapple.
Rear Admiral Kaye Edden, the Commandant of the Joint Services Staff
College was approached to be the Task Force Commander (TFC), but he
pointed out that the test series would primarily be a Royal Air Force
(RAF) responsibility, and that it would be more appropriate to have an
RAF officer in charge.
Wilfrid Oulton was appointed task
force commander on 6 February 1956, with the acting rank of
air vice marshal from 1 March 1956. He secured Group Captain
Richard Gething as his chief of staff.
Group Captain Cecil (Ginger) Weir was appointed Air Task Group
Commander. RAF units assigned to Grapple included two English
Electric Canberra bomber squadrons, Nos 76 and 100; two Shackleton
squadrons, Nos 206 and 240; the
Vickers Valiant bombers of No 49
Squadron; a flight of search and rescue Westland Whirlwind helicopters
of No 22 Squadron; and No 1325 Flight with three Dakota transport
planes. All would come under the command of No 160 Wing. Cook
would be the Scientific Director. Oulton held the first meeting of
the Grapple Executive Committee on
New Oxford Street
New Oxford Street in London on 21
February 1956. With pressure mounting at home and abroad for a
moratorium on testing, 1 April 1957 was set as the target
HMS Messina, the headquarters and communications ship for Operation
An advance party arrived on Christmas Island in an RAF Shackleton on
19 June 1956. The
Royal Fleet Auxiliary
Royal Fleet Auxiliary (RFA) Fort Beauharnois
followed on 23 June, and became a temporary headquarters ship. It
was ultimately joined by four more RFAs, Fort Constantine, Gold
Ranger, Fort Rosalie, Wave Prince and Salvictor. The role of
headquarters ship was assumed by the
Landing Ship, Tank
Landing Ship, Tank (LST) HMS
Messina, which arrived on 7 December 1956. She was fitted out with
special radio equipment to contact the United Kingdom. She carried
large refrigerators on her tank deck for storage of fresh and frozen
produce, and could supply 100 long tons (100 t) of potable water
The light aircraft carrier HMS Warrior was the operation control
ship, and the flagship of Commodore Peter Gretton, the overall Naval
Task Group commander. She embarked three Grumman TBF Avenger
attack aircraft and four Whirlwind helicopters, along with two RAF
Whirlwinds from No 22 Squadron. Damage caused by a storm in the North
Atlantic necessitated repairs in Kingston, Jamaica. By the time they
were complete, there was insufficient time to sail around Cape Horn,
so she traversed the Panama Canal, passing through the narrowest locks
with just inches to spare. HMS Narvik would reprise the role of
control ship it had in Hurricane; but it was also required for Mosaic,
and had very little time to return to the
Chatham Dockyard for a refit
before heading out to Christmas Island for Grapple. In addition
there were the frigates HMS Alert and HMS Cook, and Royal
New Zealand Navy frigates HMNZS Pukaki and Rotoiti.
HMS Warrior, a Colossus-class light aircraft carrier, was the
headquarters ship for Britain's atom hydrogen tests on Christmas
The RAF and
Royal Engineers improved the airfield to enable it to
operate large, heavily loaded aircraft, and the port and facilities
would be improved to enable Christmas Island to operate as a base by 1
December 1956. It was estimated that 18,640 measurement tons
(21,110 m3) of stores would be required for the construction
effort alone. A dredge to clear the harbour was towed from
Australia. Base development included improvements to the road
system, and establishing an electricity supply, fresh water
distillation plant, sewerage system and cold storage. The population
of the island would peak at 3,000. The Army Task Group was commanded
by Colonel J. E. S. (Jack) Stone; Colonel John Woollett was the
garrison commander. The construction force was built around 38
Corps Engineer Regiment, with the 48, 59 and 61 Field Squadrons, and
63 Field Park Squadron, and 12 and 73 Independent Field
Squadrons. Part of 25 Engineer Regiment also
deployed. They were augmented by two construction troops from
the Republic of Fiji Military Forces. With work on the plantations
halted for the duration of Operation Grapple, the Gilbertese civilians
were also employed on construction works and unloading the barges.
The troopship SS Devonshire sailed to the Central Pacific from East
Asia. At Singapore she embarked 55 Field Squadron, which came from
Korea, having been left behind there when the rest of 28 Engineer
Regiment had returned to England after supporting the 1st Commonwealth
Division in the Korean War. It also embarked
Royal Marines Landing
Craft Mechanized (LCM) crews from Poole. Heavy engineering plant and
equipment was loaded on the SS Reginald Kerr, an LST converted to
civilian use. Devonshire docked in Fiji, where it took on some sappers
who had flown ahead, and an RAF medical team. Devonshire reached
Christmas Island on 24 December, followed by Reginald Kerr, with
Woollett on board. By the end of December 1956, there nearly 4,000
personnel on Christmas Island, including two women from the
Women's Voluntary Services.
View from a RAF
Handley Page Hastings
Handley Page Hastings transport flying over Christmas
Island in August 1956.
The first project, which was finished in October, was to rebuild the
main runway at the airport to handle Valiants. This involved levelling
a surface to extend it to 2,150 yards (1,970 m) long and 60 yards
(55 m) wide. Some 20 miles (32 km) of access roads were
built, and 700,000 square yards (590,000 m2) of scrub were
cleared. Existing buildings were refurbished, and new ones erected to
provided 7,000 square yards (5,900 m2) of building space. Twelve
105,000-imperial-gallon (480,000 l) storage tanks were provided
for petrol, diesel and aviation fuel, along with pumping stations. The
main camp consisted of over 700 tents and marquees, along with 40,000
square feet (3,700 m2) of hutted accommodation. The airbase was
ready to accommodate the Valiants and their crews by March 1957. The
port was managed by 51 Port Detachment. No 504 Postal Unit, which had
a detachment at Hickam Air Force Base, a United States Air Force
(USAF) base in the American Territory of Hawaii, handled the receipt
and despatch of mail, while No 2
Special Air Formation Signal Troop
provided communications support. The
Royal Army Service Corps
Royal Army Service Corps provided
a butchery, a bakery and a laundry. They also operated DUKWs,
amphibious trucks which worked alongside the LCMs.
While Christmas Island was the main base, the area around Malden
Island 400 nautical miles (740 km) to the south was to be the
site for the bomber-dropped tests, and Penrhyn Island, 200
nautical miles (370 km) farther south was used as a technical
monitoring site and as a weather station. A USAF special weapons
monitoring team was based here, and the airstrip was improved to allow
Douglas C-124 Globemaster II
Douglas C-124 Globemaster II to use it. The Task
Force received generous support from the United States Army, Navy and
USAF. RAF aircraft were allowed to overfly the United States, even
when carrying radioactive or explosive materials, thereby obviating
the need for winterisation for the more northerly journey over Canada.
RAF ground crews were accommodated at Hickham and Travis Air Force
Base in California, and a regular aerial courier service operated from
Hickham to Christmas Island. Warrior had repairs made at Pearl Harbor,
and the US Army base at Fort DeRussy gave Woollett use of its
Royal Engineers construct the airfield runway
Having decided on a location and date, there still remained the matter
of what would be tested. John Challens, whose weapons electronics
Aldermaston had to produce the bomb assembly, wanted to know
the configuration of Green Granite. Cook ruled that it would use a Red
Beard Tom, and would fit inside a Blue Danube casing for air dropping.
The design was frozen in April 1956. There were two versions of Orange
Herald, large and small. They had similar cores, but the large version
contained more explosive. Both designs were frozen in July. The Green
Bamboo design was also nominally frozen, but tinkering with it
continued. On 3 September,
John Corner suggested that Green Granite
could be made smaller by moving the Tom and Dick closer together. This
design became known as Short Granite.
By January 1957, with the tests just months away, a tentative schedule
had emerged. Short Granite would be fired first.
Green Bamboo would
follow if Short Granite was unsuccessful, but be omitted as
Orange Herald (small) would be fired next.
Because Short Granite was too large to fit into a missile or guided
bomb, this would occur whether or not Short Granite was a success.
Finally, Green Granite would be tested. In December 1956, Cook had
proposed another design, known as Green Granite II. This was smaller
than Green Granite I, and could fit into a Yellow Sun casing that
could be used by the Blue Steel guided missile then under development;
but it could not be made ready to reach Christmas Island before 26
June 1957, and extending
Operation Grapple would cost another £1.5
About 60 Gilbertese civilians were relocated to
Fanning island in
January 1957 on the copra ship Tungaru, and another 40 on the Tulgai
the following month. By mid-March 44 Gilbertese men, 29 women and 56
children remained. By the end of April, 31 of the men, and all the
women and children hadd been taken to Fanning Island by RAF Hastings.
The civilians would remain there for the next three months, before
returning to Christmas Island. During the later test series,
the Gilbertese civilians remained on the island, marshalled in areas
like the military personnel.
The first trial series consisted of three shots. All bombs were
dropped and detonated over Malden Island, and exploded high in the
atmosphere, rather than being detonated on the ground, in order to
reduce the production of nuclear fallout. British scientists were
aware that the Americans had been able to reduce fallout by obtaining
most of the bomb yield from fusion instead of fission, but they did
not yet know how to do this. Amid growing public concern about the
dangers of fallout, particularly from strontium-90 entering the food
chain, a committee chaired by Sir
Harold Himsworth was asked to look
into the matter. Another, in the United States chaired by Detlev
Bronk, also investigated. They reported simultaneously on 12 June
1956. While differing on many points, they agreed that levels of
strontium-90 were not yet sufficiently high to be of concern.
The Grapple 2 test on 31 May 1957 of Orange Herald, as reported by
Universal International Newsreel
At an altitude of 8,000 feet (2,400 m), the fireball would not
touch the ground, thereby minimising fallout. The bombs would be
detonated with a clockwork timer rather than a barometric switch. This
meant that they had to be dropped from 45,000 feet
(14,000 m). Grapple was Britain's second airdrop of a
nuclear bomb after the Operation Buffalo test at
Maralinga on 11
October 1956, and the first of a thermonuclear weapon. The United
States had not attempted this until the
Operation Redwing Cherokee
test on 21 May 1956, and the bomb had landed 4 miles (6.4 km)
from the target.
Aldermaston wanted the bomb within 300 yards
(270 m) of the target, and Oulton felt that a good bomber crew
could achieve that. A 550-by-600-nautical-mile (1,020 by
1,110 km) exclusion zone was established, covering the area
between 3.5° North and 7.5° South and 154° and 163° West, which
was patrolled by Shackletons.
No 49 Squadron had eight Valiants, but only four deployed: XD818,
piloted by Wing Commander Kenneth Hubbard, the squadron commander;
XD822, piloted by
Squadron Leader L. D. (Dave) Roberts; XD823, piloted
Squadron Leader Arthur Steele; and XD824, piloted by Squadron
Leader Barney Millett. The other four Valiants remained at RAF
Wittering, where they were used as courier aircraft for bomb
components. The last components for Short Granite were
delivered by Valiant courier on 10 May 1957—three days late owing to
severe head winds between San Francisco and Honolulu. A full-scale
rehearsal was held on 11 May, and on 14 May it was decided to
conduct the Grapple 1 test the following day. The eight official
observers—two each from Australia, Canada, New Zealand and the
United States—were flown from Honolulu to Christmas Island in a
Handley Page Hastings, then to
Malden Island in a Dakota, from whence
DUKW took them out to HMS Alert, the spectator ship. All but a small
party were evacuated from Malden by HMS Warrior, Narvik and Messina by
19:00 on 14 May. The rest were picked up by a helicopter from
Warrior at 07:45 on 15 May. Oulton and Cook arrived on Malden by
Dakota at 08:25, where they were met by a helicopter and taken to
The Grapple 1 mission was flown by Hubbard in XD818, with Millett and
XD824 as the "grandstand" observation aircraft. The two
bombers took off from Christmas Island at 09:00. The bomb was
dropped from 45,000 feet (14,000 m) off the shore of Malden
Island at 10:38 local time on 15 May 1957. Hubbard missed the
target by 418 yards (382 m). The bomb's yield was estimated at
300 kilotonnes of TNT (1,300 TJ), far below its designed
capability. Penney cancelled the Green Granite test and
substituted a new weapon codenamed Purple Granite. This was identical
to Short Granite, but with some minor modification to its Dick;
additional uranium-235 was added, and the outer layer was replaced
with aluminium. Despite its failure, the test was hailed as a
successful thermonuclear explosion, and the government did not confirm
or deny reports that the UK had become a third thermonuclear
power. When documents on the series began to be declassified in
the 1990s, the tests were denounced as a hoax intended to deceive the
Americans into resuming nuclear cooperation; but the reports
would not have fooled the Americans observers, who helped to
analyse samples from the radioactive cloud.
Vickers Valiant B1 XD818 at RAF Museum Cosford
The next test was Grapple 2, of
Orange Herald (small). For this test,
two Fijian official observers were added. A detachment of 39 Fijian
Navy ratings who had been on board RNZN Pukaki and Roititi was
transferred to HMS Warrior. This time there were also media
representatives present on HMS Alert, including
Chapman Pincher and
Orange Herald bomb components arrived in three
separate loads on 13 May. Assembling them took two weeks. The bomb
was dropped by XD822, piloted by Roberts. XD823, piloted by Steele
acted as the grandstand aircraft. This bomb was dropped at 10:44 local
time on 31 May. After the bomb was released, Roberts made the
standard 60° banked turn to get away, but his accelerometer failed,
and the aircraft went into a high speed stall. This was potentially
disastrous, but through skilful flying Roberts was able to recover
from the stall and use the mechanical accelerometer to complete the
manoeuvre. The 720-to-800-kilotonne-of-TNT (3,000 to
3,300 TJ) yield was the largest ever achieved by a single stage
device. This made it technically a megaton weapon; but it was
close to Corner's estimate for an unboosted yield, there were doubts
that the lithium-6 deuteride had contributed at all. This was
chalked up to Taylor instability, which limited the compression of the
light elements in the core. The bomb was hailed as a hydrogen
bomb, and the truth that it was actually a large fission bomb was kept
secret by the British government until the end of the Cold
The third and final shot of the series was Grapple 3, the test of
Purple Granite. This was dropped on 19 June by a Valiant XD823 piloted
by Steele, with Millett and XD824 as the grandstand aircraft.
The yield was a very disappointing 300 kilotonnes of TNT
(1,300 TJ), even less than Short Granite. The changes had not
worked. "We haven't got it right", Cook told a flabbergasted
Oulton. "We shall have to do it all again, providing we can do so
before the ban comes into force; so that means as soon as
The next test series consisted of a single trial known as Grapple X.
To save time and money, and as HMS Warrior, Alert and Narvik, were
unavailable, it was decided to drop the bomb off the southern tip
of Christmas Island rather than off Malden Island. This was just 20
nautical miles (37 km; 23 mi) from the airfield where 3,000
men were based. This required another major construction effort
to improve the facilities on Christmas Island, and some of those that
had been constructed on
Malden Island had to now be duplicated on
Christmas Island. Works included 26 blast-proof shelters, a
control room, and tented accommodation. To provide some means of
chasing away intruders, the destroyer HMS Cossack was
allotted. HMNZS Rotoiti and Pukaki reprised their role as weather
ships. A cargo ship, the SS Somersby was chartered to bring
tentage and stores to Christmas Island. Monitoring equipment was set
Malden Island and Fanning Island, and the observation posts on
Penrhyn Island and
Jarvis Island were re-established. Oulton
[T]he rumour had gone around the force that there were to be further
tests and that they would have to remain much longer on Christmas.
This was apparently confirmed by the preparations to build the air
strip in the south of the island. The cheerful
put-up-with-the-snags-and-get-on-with-this-important-job attitude of
all ranks was changing to a sullen resentment. The troops of all three
services had had a pretty miserable time, despite all efforts to the
contrary, but had been buoyed up by the belief that the task was of
great national importance and the sooner they got the three tests
done, the sooner they could go home.
The destroyer HMS Cossack
While some ships and units such as No 49 Squadron returned to the UK,
most personnel had to remain on Christmas Island. The Minister of
Supply gave assurances that no personnel would have to remain on the
island for more than a year unless absolutely necessary, in which case
home leave would be given. To maintain morale, units were given
periodic briefings on the importance of their work. Junior officers
took a keen interest in the welfare of the men and their families at
home, since they were not permitted to bring them to the island. An
efficient mail system was maintained to allow them to keep in contact.
The quality of Army rations was better than at any other British base.
The men were given one day a week off work, and sports such as soccer,
cricket, tennis, volleyball sailing, fishing and water skiing were
organised. Leave was provided that could be taken in Fiji, Hawaii or
the Gilbert Islands. To relieve the monotony, some Army personnel
ashore exchanged places with some Navy personnel afloat. A Christmas
Island Broadcasting Service was established with nightly radio
The scientists at
Aldermaston had not yet mastered the design of
thermonuclear weapons. Knowing that much of the yield of American and
Soviet bombs came from fission in the uranium-238 tamper, they had
focused on what they called the "lithium-uranium cycle", whereby
neutrons from the fission of uranium would trigger fusion, which would
produce more neutrons to induce fission in the tamper. However, this
is not the most important reaction. Corner and his theoretical
Aldermaston argued that Green Granite could be made to
work by increasing compression and reducing Taylor instability. The
first step would be achieved with an improved Tom. The Red Beard Tom
was given an improved high explosive supercharge, a composite
uranium-235 and plutonium core, and a beryllium tamper, thereby
increasing its yield to 45 kilotonnes of TNT (190 TJ). The Dick
was greatly simplified; instead of the 14 layers in Short Granite, it
would have just three. This was called Round A; a five-layer
version was also mooted, which was called Round B. A third Round,
Round C, was produced, which was a diagnostic round. It had the same
three layers as Round A, but an inert layer instead of lithium
deuteride. Grapple X would test Round A. Components of Rounds A
and C were delivered to Christmas Island on 24, 27 and 29 October. On
inspection, a fault was found in the Round A Tom, and the fissile core
was replaced with the one from Round C.
An Avro Shackleton
This time there was no media presence, and only two foreign
observers, Rear Admiral Patrick from the US Navy, and Brigadier
General John W. White from the USAF. As the final preparations
were being made for the test on 8 November, Oulton was advised at
01:00 that a Shackleton had sighted the SS Effie, an old Victory ship
now flying the Liberian flag, in the exclusion zone. Eager to minimise
publicity before this test, the British government had delayed sending
out the Notice to Mariners, which had only been issued three weeks
before. This failed to take into account the size of the Pacific
Ocean; Effie had left its last port of call before it had been issued.
The Shackleton kept Effie under observation while trying to contact
her, and Cossack was sent to intercept. By 06:00, all was in readiness
for the test, but there was no news of Effie. Finally, at 06:15, word
was received from the Shackleton that the crew had woken up and Effie
had turned about and was now headed due south, out of the exclusion
zone at 12 knots (22 km/h). A report from the Shackleton at 07:25
indicated that Effie was now sailing in company with
By this time the Valiants had started their engines; they took off at
07:35, and were on the way when Cossack reported that Effie had
cleared the area. The bomb was dropped from Valiant XD824,
piloted by Millett, at 08:47 on 8 November 1957; Flight Lieutenant R.
Bates flew the grandstand Valiant XD825. This time the yield
of 1.8 megatonnes of TNT (7.5 PJ) exceeded expectations; the
predicted yield had only been 1 megatonne of TNT (4.2 PJ). But it
was still below the 2 megatonnes of TNT (8.4 PJ) safety limit.
This was the real hydrogen bomb Britain wanted, but it used a
relatively large quantity of expensive highly enriched uranium. Due to
the higher-than-expected yield of the explosion, there was some damage
to buildings, the fuel storage tanks, and helicopters on the
The physicists at
Aldermaston had plenty of ideas about how to follow
up Grapple X. Possibilities were discussed in September 1957. One was
to tinker with the width of the shells in the Dick to find an optimal
configuration. If they were too thick, they would slow the neutrons
generated by the fusion reaction; if they were too thin, they would
give rise to Taylor instability. Another was to do away with the
shells entirely and use a mixture of uranium-235, uranium-238 and
deuterium. Ken Allen had an idea, which
Samuel Curran supported, of a
three-layer Dick that used lithium deuteride that was less enriched in
lithium-6 (and therefore had more lithium-7), but more of it, reducing
the amount of uranium-235 in the centre of the core. This proposal was
the one adopted in October, and it became known as "Dickens" because
it used Ken's Dick. The device would otherwise be similar to Round A,
but with a larger radiation case. The safety limit was again set to 2
megatonnes of TNT (8.4 PJ). Keith Roberts calculated that the
yield could reach 3 megatonnes of TNT (13 PJ), and suggested that
this could be reduced by modifying the tamper, but Cook opposed this,
fearing that it might cause the test to fail. Because of the
possibility of a moratorium on testing, plans for the test, codenamed
Grapple Y, were restricted to the Prime Minister, who gave verbal
approval, and a handful of officials.
New Zealand National Party
New Zealand National Party lost the 1957 election, and Walter Nash
became Prime Minister. His
New Zealand Labour Party
New Zealand Labour Party had endorsed a
call by the British Labour Party for a moratorium on nuclear testing,
but he felt obligated to honour commitments made by his predecessors
to support the British nuclear testing programme. However, HMNZS
Rotoiti was unavailable, as it was joining the Far East Strategic
Reserve; its place would be taken by the destroyer
HMS Ulysses. Air Vice Marshal
John Grandy succeeded Oulton
as Task Force commander, and
Air Commodore Jack Roulston became the
Air Task Force Commander. The bomb was dropped off Christmas
at 10:05 local time on 28 April 1958 by a Valiant piloted by Squadron
Leader Bob Bates. It had an explosive yield of about 3
megatonnes of TNT (13 PJ), and remains the largest British
nuclear weapon ever tested. The design of Grapple Y was notably
successful because much of its yield came from its thermonuclear
reaction instead of fission of a heavy uranium-238 tamper, making it a
true hydrogen bomb, and because its yield had been closely
predicted—indicating that its designers understood what they were
Grapple Z series
On 22 August 1958, U.S. President
Dwight D. Eisenhower
Dwight D. Eisenhower announced a
one-year moratorium on nuclear testing, effective 31 October 1958, if
the Soviet Union and the United Kingdom also agreed to suspend
testing. Britain had already indicated that it would do so, and the
Soviet Union agreed on 30 August. This did not mean an immediate
end to testing; on the contrary, all three all rushed to perform as
much testing as possible before the deadline. The British
scientists needed to gather as much data as possible to allow them to
design production nuclear weapons. Moreover, as the prospect of
increased American cooperation grew after October 1957, they knew that
the quality and quantity of what the Americans would share would
depend on what they had to offer. A new British test series, known as
Grapple Z, commenced on 22 August. It explored new technologies such
as the use of external neutron initiators, which had first been tried
out with Orange Herald. Core boosting using tritium gas and external
boosting with layers of lithium deuteride permitted a smaller, lighter
Tom for two-stage devices. It would be the biggest and most complex
British test series.
The East Point balloon anchor on Christmas Island. Bombs were hoisted
by balloons from here.
Of particular concern was radiation damage, known as the RI effect.
Keith Roberts and Bryan Taylor at
Aldermaston had discovered that
flash of radiation from the detonation of an atomic bomb could affect
a nearby bomb. This opened up the possibility of a missile warhead
being disabled by another launched for this purpose. Plutonium cores
were especially vulnerable, as they were already prone to
predetonation. This had the potential to render Britain's nuclear
deterrent ineffective. This discovery was given the highest level of
Aldermaston would spend much of the next few years
working on the problem. To build a primary immune to this effect would
require techniques that
Aldermaston had not yet mastered. The
number of tests in the series was assumed to be four for planning
purposes, but as late as May the Prime Minister had only approved two
shots, tentatively scheduled for 15 August and 1 September 1958.
Four Valiants, XD818, XD822, XD824 and XD827, deployed to Christmas
Island, the last of which arrived on 31 July.
The first shot was a test of Pendant, a fission bomb boosted with
solid lithium hydride intended as a primary for a thermonuclear
bomb. Rather than being dropped from a bomber, this bomb was
suspended from a string of four vertically stacked barrage balloons.
This was chosen over an air drop because the bomb assembly could not
be fitted into a dropable casing, but it introduced a host of
problems. A balloon shot had been tried only once before by the
British, during Operation Antler at
Maralinga in October 1957. William
Aldermaston was placed in charge of the balloon crews, who
commenced training at
RAF Cardington in
Bedfordshire in January 1958.
Inflating the balloons required 1,200 cylinders of hydrogen gas, and
there were no reserves. If another balloon test were required, then
the empty cylinders would have to be returned to the United Kingdom
for refilling, and then shipped out again. An important consideration
was how they could be shot down if they broke loose of their moorings
with a live hydrogen bomb. The cargo ship SS Tidecrest arrived at
Christmas Island on 20 July, but the firing harness was lost at San
Francisco International Airport on 1 August, and a replacement had to
be flown out. The Pendant fissile core arrived by air on 12
August, and the weapon was assembled with its external neutron
initiator unit. On 22 August 1958 it was lifted 1,500 feet
(460 m) in the air, and it detonated at 09:00. The yield was
assessed at 24 kilotonnes of TNT (100 TJ).
The next shot, was of Flagpole, an unboosted version of Orange Herald
known as Indigo Herald. It was air dropped by Valiant XD822,
Squadron Leader Bill Bailey, with XD818 flown by Flight
Lieutenant Tiff O'Connor as the grandstand aircraft, on 2 September
1958. This was the first live drop of a British nuclear weapon using
blind radar technique. Bailey managed to put the bomb 95 yards
(87 m) from the target. It detonated at 8,500 feet
(2,600 m) at 08:24 with a yield of about 1.2 megatonnes of TNT
The third shot was of Halliard, an unusual three-stage design with two
nuclear-fission components followed by a thermonuclear stage that was
supposedly immune to exposure from another bomb despite its not using
boosting. The Americans had indicated an interest in it.
Macmillan noted in his diary:
Meeting of atomic experts, just returned from US. Two important facts
emerged: (a) Americans are doing ten more kiloton tests before the end
of October and would not wish us to stop before them; (b) in some
respects we are as far, and even further, advanced in the art than our
American friends. They thought interchange of information would be all
give. They are keen that we should complete our series, especially the
last megaton, the character of which is novel and of deep interest to
them. This is important, because it makes this final series
complementary rather than competitive—and therefore easy to defend
The success of blind bombing in Flagpole led to Grandy deciding to use
the blind radar technique again. Hubbard was less sure. In 52 practice
drops with blind radar, the average error had been 235 yards
(215 m) as opposed to 245 yards (224 m) with visual bombing.
The problem for the aircrew was that they would be dropping a live
hydrogen bomb—generally considered a dangerous thing to do—with no
means of verifying that their instruments were correct. Air Chief
Marshal Sir Harry Broadhurst, the head of
Bomber Command, wished
O'Connor luck; his XD827 would make the drop, with Squadron Leader
Tony Caillard in XD827, the grandstand aircraft. The aircraft took off
at 07:15 on 11 September 1958. Once in the air, though, a fault
developed in the ground radar transmitter. Grandy then authorised a
visual drop. It was later confirmed that it was 260 yards (240 m)
from the target.  It was detonated at 8,500 feet (2,600 m)
at 08:49 with a yield of about 800 kilotonnes of TNT (3,300 TJ),
very close to the predicted yield of 750 kilotonnes of TNT
The final test in the Grapple Z series was of Burgee, at 09:00 on 23
September 1958. This was another balloon-borne test. Burgee was an
atomic bomb boosted with gaseous tritium created by a generator
codenamed Daffodil. It had a yield of about 25 kilotonnes of TNT
(100 TJ). The
Aldermaston weapon makers had now demonstrated all
of the technologies that were needed to produce a megaton hydrogen
bomb that weighed no more than 1 long ton (1.0 t) and was immune
to premature detonation caused by nearby nuclear explosions. The
international moratorium commenced on 31 October 1958, and Britain
never resumed atmospheric testing.
Cooperation with the United States
Main article: 1958 US-UK Mutual Defence Agreement
Dwight D. Eisenhower
Dwight D. Eisenhower and British Prime Minister Harold
Macmillan meet for talks in Bermuda in March 1957, partly to repair
Anglo-American relations after the disastrous
Suez Crisis of the
British timing was good. The Soviet Union's launch of Sputnik 1, the
world's first artificial satellite, on 4 October 1957, came as a
tremendous shock to the American public, who had trusted that American
technological superiority ensured their invulnerability. Now,
suddenly, there was incontrovertible proof that, in some areas at
least, the Soviet Union was actually ahead. In the widespread calls
for action in response to the Sputnik crisis, officials in the United
States and Britain seized an opportunity to mend the relationship with
Britain that had been damaged by the Suez Crisis. At the
suggestion of Harold Caccia, the British Ambassador to the United
States, Macmillan wrote to Eisenhower on 10 October urging that the
two countries pool their resources to meet the challenge. To do this,
the McMahon Act's restrictions on nuclear cooperation needed to be
relaxed. British information security, or the lack thereof, no
longer seemed so important now that the Soviet Union was apparently
ahead, and the United Kingdom had independently developed the hydrogen
bomb. The trenchant opposition from the Joint Committee on Atomic
Energy that had derailed previous attempts was absent. Amendments
to the Atomic Energy Act of 1954 passed Congress on 30 June 1958, and
were signed into law by Eisenhower on 2 July 1958. The 1958
US–UK Mutual Defence Agreement was signed on 3 July, and was
approved by Congress on 30 July. Macmillan called this "the Great
Special Relationship proved mutually beneficial,
although it was never one of equals; the United States was far larger
than Britain both militarily and economically. Britain soon became
dependent on the United States for its nuclear weapons, as it lacked
the resources to produce a range of designs. The British decided
to adapt the Mark 28 as a British weapon as a cheaper alternative to
doing their own development, which became Red Snow. Other weapons
were supplied through Project E, under which weapons in American
custody were supplied for the use of the RAF and British
Army. Nuclear material was also acquired from the United
States. Under the Mutual Defence Agreement 5.4 tonnes of UK
produced plutonium was sent to the US in return for 6.7 kilograms
(15 lb) of tritium and 7.5 tonnes of highly enriched uranium
between 1960 and 1979, replacing production of the British uranium
enrichment facility at
Capenhurst , although much of the highly
enriched uranium was used not for weapons, but as fuel for the growing
UK fleet of nuclear submarines. The British ultimately acquired
entire weapons systems, with the
UK Polaris programme
UK Polaris programme and Trident
nuclear programme using American missiles with British nuclear
In 2005, a
Massey University study in New Zealand concluded that
sailors from the Royal Navy,
Royal New Zealand Navy
Royal New Zealand Navy and Fijian Navy
who observed the tests from nearby ships later suffered adverse health
effects from exposure to radioactive fallout, including cancer and
genetic abnormalities in the veterans' children. Various veterans'
organisations filed a class action lawsuit against the UK Ministry of
Defence following the publication of the study. The
effects of radioactive fallout from the Grapple tests were researched
by a 2010 British Government study that concluded the fallout did not
reach concentrations that could affect the surrounding nature. The
Ministry of Defence maintained that few people were exposed to any
radiation or contamination at all, and that studies had shown little
or no health effects. An analysis of illnesses in veterans
of Grapple and other weapons tests produced statistics that are hard
to interpret. The veterans showed rates of illness that were slightly
higher than the control group, but the control group had lower rates
of illness than the population as a whole while the veterans had rates
that were about the same. Neither of these results has a clear
In 1993, two British veterans of Operation Grapple, Ken McGinley, a
veteran of five of the tests, and Edward Egan, a veteran of Grapple Y,
sued for £100,000 damages over multiple health problems which their
attributed to their involvement in the tests. They took their claim to
the European Court of Human Rights, which rejected it in a 5-4 split
decision on 9 June 1998. An appeal to the court to re-open
the case was declined in January 2000. A group of 1,011 British
ex-servicemen were denied permission to sue the UK Ministry of Defence
by the Supreme Court in March 2012, on the grounds that too much time
had elapsed since they became aware of their medical conditions, under
the terms of the Limitation Act 1980. In January 2015, the Prime
Minister of Fiji, Frank Bainimarama, announced that the Fijian
government would provide Fiji $9,855 (US $4,788) compensation payments
to the 24 surviving Fijian servicemen who participated in Operation
In addition to the British tests during Operation Grapple, the United
States used Christmas Island for nuclear testing in Operation Dominic
in 1962. Twenty-four nuclear bombs were detonated near Christmas
Island as part of this test series. In 1979, the Gilbert Islands,
Phoenix Islands and Line Islands, which included Christmas Island and
Malden Island, became independent of the United Kingdom as the
Republic of Kiribati. By the 1980s, there was a permanent population
of around 1,200 the majority of whom were Gilbertese. The spelling of
the name of the island was changed to Kirimati, the Gilbertese form of
Malden Island is uninhabited.
Penrhyn Island is part of the
Cook Islands, a self-governing dependency of New Zealand.
United Kingdom's Grapple series tests and detonations
Date time (UTC)
Elevation + height
000000001957-05-15-000015 May 1957 19:37
Malden Island, Kiribati
4°03′S 154°54′W / 4.05°S 154.9°W / -4.05; -154.9
002203 !3 m (9.8 ft) + 2,200 m (7,200 ft)
003000000 !300 kt
Attempted thermonuclear detonation, most of output from the secondary,
but disappointing small yield overall.
000000001957-05-31-000031 May 1957 19:41
Malden Island, Kiribati
4°03′S 154°54′W / 4.05°S 154.9°W / -4.05; -154.9
002403 !3 m (9.8 ft) + 2,400 m (7,900 ft)
007200000 !720 kt
Large fission device
000000001957-06-19-000019 June 1957 19:40
Malden Island, Kiribati
4°03′S 154°54′W / 4.05°S 154.9°W / -4.05; -154.9
002403 !3 m (9.8 ft) + 2,400 m (7,900 ft)
002000000 !200 kt
Attempt at fixing the Short Granite device, also unsuccessful
000000001957-11-08-00008 November 1957 17:47
Kiritimati (Christmas Island), Kiribati
1°40′43″N 157°13′59″W / 1.67851°N 157.23303°W /
1.67851; -157.23303 (X/Round C)
002253 !3 m (9.8 ft) + 2,250 m (7,380 ft)
018000000 !1.8 Mt
First successful British thermonuclear bomb.
000000001958-04-28-000028 April 1958 19:05
Kiritimati (Christmas Island), Kiribati
1°40′15″N 157°14′14″W / 1.6709°N 157.23726°W /
1.6709; -157.23726 (Y)
002353 !3 m (9.8 ft) + 2,350 m (7,710 ft)
030000000 !3 Mt
Largest yield from a British thermonuclear device
000000001958-08-22-000022 August 1958 18:00
Kiritimati (Christmas Island), Kiribati
1°43′46″N 157°12′38″W / 1.72934°N 157.21065°W /
1.72934; -157.21065 (Z1/Pennant 2)
000453 !3 m (9.8 ft) + 450 m (1,480 ft)
000240000 !24 kt
000000001958-09-02-00002 September 1958 17:24
Kiritimati (Christmas Island), Kiribati
1°40′10″N 157°13′39″W / 1.66932°N 157.22742°W /
1.66932; -157.22742 (Z2/Flagpole 1)
002853 !3 m (9.8 ft) + 2,850 m (9,350 ft)
010000000 !1 Mt
000000001958-09-11-000011 September 1958 17:49
Kiritimati (Christmas Island), Kiribati
1°39′09″N 157°13′25″W / 1.65248°N 157.22374°W /
1.65248; -157.22374 (Z3/HALYARD 1)
002653 !3 m (9.8 ft) + 2,650 m (8,690 ft)
008000000 !800 kt
000000001958-09-23-000023 September 1958 18:00
Kiritimati (Christmas Island), Kiribati
1°45′07″N 157°11′17″W / 1.75194°N 157.18819°W /
1.75194; -157.18819 (Z4/Burgee 2)
000453 !3 m (9.8 ft) + 450 m (1,480 ft)
000250000 !25 kt
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