The 21st Army Group was a British headquarters formation formed during the

Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. It controlled two

field armies A field army (or numbered army or simply army) is a military formation in many armed forces, composed of two or more corps and may be subordinate to an army group. Likewise, air armies are equivalent formation within some air forces, and with ...

and other supporting units, consisting primarily of the

British Second Army The British Second Army was a field army active during the First and Second World Wars. During the First World War the army was active on the Western Front throughout most of the war and later active in Italy. During the Second World War the army ...

and the First Canadian Army. Established in London during July 1943, under the command of Supreme Headquarters Allied Expeditionary Force (SHAEF), it was assigned to Operation Overlord, the Western Allied invasion of Europe, and was an important

Allied An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out among them. Members of an alliance are called ...

force in the

European Theatre The European theatre of World War II was one of the two main theatres of combat during World War II. It saw heavy fighting across Europe for almost six years, starting with Germany's invasion of Poland on 1 September 1939 and ending with the ...

. At various times during its existence, the 21st Army Group had additional British, Canadian,

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

and

Polish Polish may refer to: * Anything from or related to Poland, a country in Europe * Polish language * Poles Poles,, ; singular masculine: ''Polak'', singular feminine: ''Polka'' or Polish people, are a West Slavic nation and ethnic group, w ...

corps Corps (; plural ''corps'' ; from French , from the Latin "body") is a term used for several different kinds of organization. A military innovation by Napoleon I, the formation was first named as such in 1805. The size of a corps varies great ...

attached to it. The 21st Army Group operated in Northern France, Luxembourg, Belgium, the Netherlands and Germany from June 1944 until August 1945, when it was renamed the

British Army of the Rhine There have been two formations named British Army of the Rhine (BAOR). Both were originally occupation forces in Germany, one after the First World War and the other after the Second World War. Both formations had areas of responsibility located ...

(BAOR).

Western European theatre

Normandy

Commanded by

General A general officer is an Officer (armed forces), officer of highest military ranks, high rank in the army, armies, and in some nations' air forces, space forces, and marines or naval infantry. In some usages the term "general officer" refers t ...

(later

Field Marshal Field marshal (or field-marshal, abbreviated as FM) is the most senior military rank, ordinarily senior to the general officer ranks. Usually, it is the highest rank in an army and as such few persons are appointed to it. It is considered as ...

)

Sir ''Sir'' is a formal honorific address in English for men, derived from Sire in the High Middle Ages. Both are derived from the old French "Sieur" (Lord), brought to England by the French-speaking Normans, and which now exist in French only as ...

Bernard Montgomery, 21st Army Group initially controlled all ground forces in Operation Overlord (the

United States First Army First Army is the oldest and longest-established field army of the United States Army. It served as a theater army, having seen service in both World War I and World War II, and supplied the US army with soldiers and equipment during the Korea ...

and

). When sufficient American forces had landed, their own 12th Army Group was activated, under

Omar Bradley Omar Nelson Bradley (February 12, 1893April 8, 1981) was a senior officer of the United States Army during and after World War II, rising to the rank of General of the Army. Bradley was the first chairman of the Joint Chiefs of Staff and over ...

, and the 21st Army Group was left with the British Second Army and the newly activated First Canadian Army which, despite its title, also contained many British and Polish troops. Normandy was a battle of attrition for the British and Canadian troops, drawing in most of the available German reinforcements, especially armoured divisions, around Caen at the eastern end of the

lodgement A lodgement is an enclave, taken and defended by force of arms against determined opposition, made by increasing the size of a bridgehead, beachhead, or airhead into a substantial defended area, at least the rear parts of which are out of direc ...

. These operations left the Germans unable to prevent the American breakout at the western end of the Normandy beachhead in early August 1944. Following the German attack towards Mortain, the American breakout and an advance by the 21st Army Group the German armed forces in Normandy were nearly enveloped in the Falaise pocket, and subsequently routed, retreating towards the Low Countries.

Advance into the Low Countries

After the successful landings in the south of France by the

U.S. 6th Army Group The 6th United States Army Group was an Allies of World War II, Allied Army Group that fought in the European Theater of Operations during World War II. Made up of field army, field armies from both the United States Army and the French Army, ...

, the 21st Army Group formed the left flank of the three Allied army groups arrayed against German forces in the West. It was therefore responsible for securing the ports upon which Allied supply depended, and also with overrunning German

V-1 V1, V01 or V-1 can refer to version one (for anything) (e.g., see version control) V1, V01 or V-1 may also refer to: In aircraft * V-1 flying bomb, a World War II German weapon * V1 speed, the maximum speed at which an aircraft pilot may abort ...

and

V-2 The V-2 (german: Vergeltungswaffe 2, lit=Retaliation Weapon 2), with the technical name ''Aggregat 4'' (A-4), was the world’s first long-range guided ballistic missile. The missile, powered by a liquid-propellant rocket engine, was develope ...

launching sites along the coasts of western

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

and

Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...

. By 29 August, the Germans had largely withdrawn across the

Seine River ) , mouth_location = Le Havre/Honfleur , mouth_coordinates = , mouth_elevation = , progression = , river_system = Seine basin , basin_size = , tributaries_left = Yonne, Loing, Eure, Risle , tributaries ...

without their heavy equipment. The campaign through Northern France and Belgium was largely a pursuit, with the ports - formally designated "Fortress Towns" by the Germans - offering only limited opposition to the First Canadian Army. The advance was so rapid, 250 miles in four days, that Antwerp, Belgium, was captured undefended on 4 September 1944 and the port facilities were cleared of the German defenders in the following days. On 1 September 1944, the 21st Army Group was relieved of operational control of the American armies, and those armies formed the 12th Army Group. By mid-September, elements of 21st Army Group had reached the Dutch border, but were halted due to lack of supplies, and by flooding caused by the widespread German demolition of Dutch dikes. German control of some of the channel ports and the approaches to Antwerp, and previous Allied bombing of the French and Belgian railways, resulted in a long supply line from Normandy served mainly by

trucks A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction ...

Operation Market Garden

After the break-out from Normandy, there were high hopes that the war could be ended in 1944. In order to do so, the last great natural defensive barrier of Germany in the west, the

Rhine River ), Surselva, Graubünden, Switzerland , source1_coordinates= , source1_elevation = , source2 = Rein Posteriur/Hinterrhein , source2_location = Paradies Glacier, Graubünden, Switzerland , source2_coordinates= , source ...

had to be crossed. Operation Market Garden was orchestrated to attempt just this. It was staged in the

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

with the

airborne troops Airborne forces, airborne troops, or airborne infantry are ground combat units carried by aircraft and airdropped into battle zones, typically by parachute drop or air assault. Parachute-qualified infantry and support personnel serving in a ...

of the American 82nd and

101st The 101st Airborne Division (Air Assault) ("Screaming Eagles") is a light infantry division (military), division of the United States Army that specializes in air assault military operation, operations. It can plan, coordinate, and execute mul ...

and one British 1st airborne divisions and the

1st Polish Parachute Brigade The 1st (Polish) Independent Parachute Brigade was a parachute infantry brigade of the Polish Armed Forces in the West under the command of Major General Stanisław Sosabowski, created in September 1941 during the Second World War and based in S ...

(attached to the 1st Airborne Division) being dropped to capture bridges over the lower Rhine before they could be blown by the Germans. The airborne formations were then to be relieved by armoured forces of the

Guards Armoured Division The Guards Armoured Division was an armoured division of the British Army during the Second World War. The division was created in the United Kingdom on 17 June 1941 during the Second World War from elements of the Guards units, the Grenadier ...

advancing rapidly northwards through

Eindhoven Eindhoven () is a city and municipality in the Netherlands, located in the southern province of North Brabant of which it is its largest. With a population of 238,326 on 1 January 2022,Nijmegen to

Arnhem Arnhem ( or ; german: Arnheim; South Guelderish: ''Èrnem'') is a city and municipality situated in the eastern part of the Netherlands about 55 km south east of Utrecht. It is the capital of the province of Gelderland, located on both ban ...

, opening the north German plains, and the industrial

Ruhr Valley The Ruhr ( ; german: Ruhrgebiet , also ''Ruhrpott'' ), also referred to as the Ruhr area, sometimes Ruhr district, Ruhr region, or Ruhr valley, is a polycentric urban area in North Rhine-Westphalia, Germany. With a population density of 2,800/km ...

, to the Allies. However, the British armoured forces had only one main highway to operate on, and crucial information about the German forces in the operational area was either missing or ignored. The scratch forces remaining after the retreat from France were much stronger than expected, thus giving the armoured units of the XXX Corps a much tougher fight than had been anticipated, slowing the advance. The 1st British Airborne Division in Arnhem was practically destroyed during the battle. The advance stopped south of the

Lower Rhine The Lower Rhine (german: Niederrhein; kilometres 660 to 1,033 of the river Rhine) flows from Bonn, Germany, to the North Sea at Hook of Holland, Netherlands (including the Nederrijn or "Nether Rhine" within the Rhine–Meuse–Scheldt delta); al ...

, resulting in a narrow salient that ran from the north of Belgium across the south-east of the Netherlands and was vulnerable to attack. German assaults in this salient, particularly north of Nijmegen were repelled. The thin salient was then expanded Eastwards with

Operation Aintree The Battle of Overloon was a battle fought in the Second World War battle between Allied forces and the German Army which took place in and around the village of Overloon in the south-east of the Netherlands between 30 September and 18 October 1 ...

which saw bitter fighting around the town of Overloon. To the West

Operation Pheasant Operation Pheasant, also known as the Liberation of North Brabant, was a major operation to clear German troops from the province of North Brabant in the Netherlands during the fighting on the Western Front in the Second World War. This offensiv ...

was conducted which resulted in the liberation of the cities of

Tilburg Tilburg () is a city and municipality in the Netherlands, in the southern province of North Brabant. With a population of 222,601 (1 July 2021), it is the second-largest city or municipality in North Brabant after Eindhoven and the seventh-larg ...

and

s-Hertogenbosch s-Hertogenbosch (), colloquially known as Den Bosch (), is a city and municipality in the Netherlands with a population of 157,486. It is the capital of the province of North Brabant and its fourth largest by population. The city is south of th ...

broadening the front line.

Battle of the Scheldt

Since the approaches to the port of Antwerp had not been cleared when the city was captured it had allowed the German army time to reorganise and dig in along the approaches making the port completely unusable. Thus an operation was needed to clear the approaches and thereby ease the supply problem. The island of

Walcheren Walcheren () is a region and former island in the Dutch province of Zeeland at the mouth of the Scheldt estuary. It lies between the Eastern Scheldt in the north and the Western Scheldt in the south and is roughly the shape of a rhombus. The two ...

was strongly held by German forces and commanded the estuary of the

Scheldt The Scheldt (french: Escaut ; nl, Schelde ) is a river that flows through northern France, western Belgium, and the southwestern part of the Netherlands, with its mouth at the North Sea. Its name is derived from an adjective corresponding to ...

which flows through Antwerp. Operations by

II Canadian Corps II Canadian Corps was a corps-level formation that, along with I (British) Corps (August 1, 1944 to April 1, 1945) and I Canadian Corps (April 6, 1943 to November 1943, and April 1, 1945 until the end of hostilities), comprised the First Canad ...

cleared the approaches to Antwerp both north and south of the water during the

Battle of the Scheldt The Battle of the Scheldt in World War II was a series of military operations led by the First Canadian Army, with Polish and British units attached, to open up the shipping route to Antwerp so that its port could be used to supply the Alli ...

. Walcheren itself was captured in late 1944 by the last major amphibious assault in Europe in the Second World War. A combination of British and Canadian forces and Royal Marines undertook the operation.

Battle of the Bulge

After the capture of Walcheren came the last great German offensive of the war in the west. In a repeat of their 1940 attack, German formations smashed through weak Allied lines in the Ardennes in Belgium. The

Battle of the Bulge The Battle of the Bulge, also known as the Ardennes Offensive, was the last major German offensive campaign on the Western Front during World War II. The battle lasted from 16 December 1944 to 28 January 1945, towards the end of the war in ...

presented a command problem to General

Eisenhower Dwight David "Ike" Eisenhower (born David Dwight Eisenhower; ; October 14, 1890 – March 28, 1969) was an American military officer and statesman who served as the 34th president of the United States from 1953 to 1961. During World War II, ...

. It had sliced through US lines, leaving some American formations north and south of the new German salient. However, the headquarters of U.S. 12th Army Group lay to the south, and so Eisenhower decided to place American forces north of the "Bulge" salient under 21st Army Group. They, with the

US Third Army The United States Army Central, formerly the Third United States Army, commonly referred to as the Third Army and as ARCENT, is a military formation of the United States Army which saw service in World War I and World War II, in the 1991 Gulf Wa ...

under General

George S. Patton George Smith Patton Jr. (November 11, 1885 – December 21, 1945) was a general in the United States Army who commanded the Seventh United States Army in the Mediterranean Theater of World War II, and the Third United States Army in France ...

, reduced the salient. After the battle, control of the First US Army which had been placed under Field Marshal Montgomery's temporary command was returned to Bradley's 12th Army Group. The

US Ninth Army The Ninth Army is a field army of the United States Army, garrisoned at Caserma Ederle, Vicenza, Italy. It is the United States Army Service Component Command of United States Africa Command (USAFRICOM or AFRICOM). Activated just eight weeks be ...

remained under Montgomery longer, before being returned to American command in Germany.

Battle for the Roer Triangle

Prior to the Rhineland Campaign the enemy had to be cleared from the

Roer Triangle The Rur or Roer (german: Rur ; Dutch and li, Roer, , ; french: Rour) is a major river that flows through portions of Belgium, Germany and the Netherlands. It is a right (eastern) tributary to the Meuse ( nl, links=no, Maas). About 90 perce ...

during

Operation Blackcock Operation Blackcock was an operation to clear German troops from the Roer Triangle, formed by the towns of Roermond and Sittard in the Netherlands and Heinsberg in Germany during the fighting on the Western Front in the Second World War. It was ...

. This large methodical mopping up operation took place between 14 and 27 January 1945. It was not planned to make any deep thrust into the enemy defences or capture large numbers of prisoners. It proceeded from stage to stage almost entirely as planned and was completed with minimal casualties.

Rhineland Campaign

Allied forces closed up to the Rhine by March 1945. 21st Army Group at this time comprised the British Second Army under General

Miles Dempsey General Sir Miles Christopher Dempsey, (15 December 1896 – 5 June 1969) was a senior British Army officer who served in both world wars. During the Second World War he commanded the Second Army in north west Europe. A highly professional an ...

, the First Canadian Army under

Harry Crerar General Henry Duncan Graham Crerar (28 April 1888 – 1 April 1965) was a senior officer of the Canadian Army who became the country's senior field commander in the Second World War as commander of the First Canadian Army in the campaign in N ...

and the US Ninth Army, under General William Simpson. The First Canadian Army executed

Operation Veritable Operation Veritable (also known as the Battle of the Reichswald) was the northern part of an Allied pincer movement that took place between 8 February and 11 March 1945 during the final stages of the Second World War. The operation was conduc ...

in difficult conditions from Nijmegen eastwards through the Reichswald Forest then southwards. This was to have been the northern part of a pincer movement with the US Ninth Army moving northwards towards

Düsseldorf Düsseldorf ( , , ; often in English sources; Low Franconian and Ripuarian: ''Düsseldörp'' ; archaic nl, Dusseldorp ) is the capital city of North Rhine-Westphalia, the most populous state of Germany. It is the second-largest city in th ...

and

Krefeld Krefeld ( , ; li, Krieëvel ), also spelled Crefeld until 1925 (though the spelling was still being used in British papers throughout the Second World War), is a city in North Rhine-Westphalia, Germany. It is located northwest of Düsseldorf, i ...

(

Operation Grenade During World War II, Operation Grenade was the crossing of the Roer river between Roermond and Düren by the U.S. Ninth Army, commanded by Lieutenant General William Hood Simpson, in February 1945, which marked the beginning of the Allied inv ...

), to clear the west bank of the Rhine north of

Cologne Cologne ( ; german: Köln ; ksh, Kölle ) is the largest city of the German western state of North Rhine-Westphalia (NRW) and the fourth-most populous city of Germany with 1.1 million inhabitants in the city proper and 3.6 millio ...

. However the Americans were delayed by two weeks when the Germans destroyed the Roer dams and flooded the American route of advance. As a result, the Canadians engaged and mauled the German reserves intended to defend the Cologne Plain. In

Operation Plunder Operation Plunder was a military operation to cross the Rhine on the night of 23 March 1945, launched by the 21st Army Group under Field Marshal Bernard Montgomery. The crossing of the river was at Rees, Wesel, and south of the river Li ...

, starting on 13 March 1945, the British Second Army and the US Ninth Army crossed the Rhine at various places north of the Ruhr and German resistance in the west quickly crumbled. The First Canadian Army wheeled left and liberated the northern part of the Netherlands and captured adjoining areas of Germany, the British Second Army occupied much of north-west Germany and the US Ninth Army formed the northern arm of the

envelopment Envelopment is the military tactic of seizing objectives in the enemy's rear with the goal of destroying specific enemy forces and denying them the ability to withdraw. Rather than attacking an enemy head-on as in a frontal assault an envelopment ...

of German forces in the Ruhr Pocket and on 4 April reverted to Omar Bradley's 12th Army Group. On 4 May 1945, Field Marshal Montgomery accepted the unconditional surrender of the German forces in the Netherlands, in north west Germany and Denmark.

British Army of the Rhine

After the German surrender, 21st Army Group was converted into the headquarters for the British occupation zone in Germany. It was renamed the

(BAOR) on 25 August 1945 and eventually formed the nucleus of the British forces stationed in Germany throughout the

Cold War The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because the ...

Order of battle

The main constituent formations of 21st Army Group were the First Canadian Army and the

. In practice, neither of the two armies were homogeneously British or Canadian. Also included was the Polish I Corps, from Normandy onwards and small Dutch, Belgian, and Czechoslovak units; units of the

US Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...

were attached from time to time. * 21st Army Group (General B.L. Montgomery) **

(General Sir M. Dempsey) ***

VIII Corps 8th Corps, Eighth Corps, or VIII Corps may refer to: * VIII Corps (Grande Armée), a unit of the Imperial French army during the Napoleonic Wars * VIII Army Corps (German Confederation) * VIII Corps (German Empire), a unit of the Imperial German Ar ...

(General R. O'Connor) **** 11th Armoured Division ****

****

15th (Scottish) Infantry Division The 15th (Scottish) Infantry Division was an infantry division of the British Army that served during the Second World War. It was raised on 2 September 1939, the day before war was declared, as part of the Territorial Army (TA) and served in ...

***

XII Corps 12th Corps, Twelfth Corps, or XII Corps may refer to: * 12th Army Corps (France) * XII Corps (Grande Armée), a corps of the Imperial French Army during the Napoleonic Wars * XII (1st Royal Saxon) Corps, a unit of the Imperial German Army * XII ...

(General N. Ritchie) **** 49th (West Riding) Infantry Division **** 53rd (Welsh) Infantry Division **** 59th (Staffordshire) Infantry Division *** XXX Corps (General G .C. Bucknall) **** 7th Armoured Division **** 43rd (Wessex) Infantry Division **** 50th (Northumbrian) Infantry Division ** First Canadian Army (General H. Crerar) ***

(General G. Simonds) **** 2nd Canadian Division **** 3rd Canadian Division ****

4th Canadian (Armoured) Division The 4th Canadian Division is a formation of the Canadian Army. The division was first created as a formation of the Canadian Corps during the World War I, First World War. During the World War II, Second World War the division was reactivated ...

**** 1st Armoured Division (Poland) ***

I Corps I Corps, 1st Corps, or First Corps may refer to: France * 1st Army Corps (France) * I Cavalry Corps (Grande Armée), a cavalry unit of the Imperial French Army during the Napoleonic Wars * I Corps (Grande Armée), a unit of the Imperial French A ...

(General G. Crocker) **** 3rd Infantry Division **** 5th Infantry Division **** 51st (Highland) Division ***

I Canadian Corps I Canadian Corps was one of the two corps fielded by the Canadian Army during the Second World War. History From December 24, 1940, until the formation of the First Canadian Army in April 1942, there was a single unnumbered Canadian Corps. I ...

**** 1st Canadian Division ****

5th Canadian (Armoured) Division Fifth is the ordinal form of the number five. Fifth or The Fifth may refer to: * Fifth Amendment to the United States Constitution, as in the expression "pleading the Fifth" * Fifth column, a political term * Fifth disease, a contagious rash that ...

Attached U.S. units

21st Army Group had American units attached at various times: # During Operation Market Garden, two U.S. airborne divisions (the

and 82nd), were deployed as part of

First Allied Airborne Army The First Allied Airborne Army was an Allied formation formed on 2 August 1944 by the order of General Dwight D. Eisenhower, the Supreme Allied Commander of the Allied Expeditionary Force. The formation was part of the Allied Expeditionary For ...

. # During

I British corps I, or i, is the ninth letter and the third vowel letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''i'' (pronounced ), plural ...

was reinforced by US 104th Infantry Division. # During the

, the U.S.

First First or 1st is the ordinal form of the number one (#1). First or 1st may also refer to: *World record, specifically the first instance of a particular achievement Arts and media Music * 1$T, American rapper, singer-songwriter, DJ, and rec ...

and Ninth Armies) on the north face of the bulge came under the control of 21st Army Group. # U.S. Ninth Army remained part of 21st Army Group during the drive to the Rhine (Operations Veritable and Grenade), the Rhine crossings (

) and the battle of the Ruhr Pocket. # U.S. 17th Airborne Division also took part in the Rhine crossings as part of

Operation Varsity Operation Varsity (24 March 1945) was a successful airborne forces operation launched by Allied troops that took place toward the end of World War II. Involving more than 16,000 paratroopers and several thousand aircraft, it was the largest ai ...

. # During

Operation Clipper During the Second World War, Operation Clipper was an Allied offensive by the British XXX Corps (which included the American 84th Infantry Division) to reduce the Geilenkirchen salient in mid-November 1944. ''Clipper'' was the preliminary to ...

, U.S. 84th Infantry Division was temporarily attached to British XXX Corps.

Commanders

* June 1943 – December 1943

Bernard Paget General Sir Bernard Charles Tolver Paget, (15 September 1887 – 16 February 1961) was a senior British Army officer who served with distinction in the First World War, and then later during the Second World War. During the latter, he command ...

* January 1944 – August 1945 General Bernard Montgomery''Montgomery and "colossal cracks": the 21st Army Group in northwest Europe'' By Stephen Hart, p.8

Citations

General sources

* * * {{Authority control Military units and formations established in 1943 Military units and formations disestablished in 1945 Army groups of the British Army in World War II