First Ostend Raid

The First Ostend Raid (part of Operation ZO) was the first of two attacks by the Royal Navy on the German-held port of Ostend during the late spring of 1918 during the First World War. Ostend was attacked in conjunction with the neighbouring harbour of Zeebrugge on 23 April in order to block the vital strategic port of Bruges, situated inland and ideally sited to conduct raiding operations on the British coastline and shipping lanes. Bruges and its satellite ports were a vital part of the German plans in their war on Allied commerce (''Handelskrieg'') because Bruges was close to the troopship lanes across the English Channel and allowed much quicker access to the Western Approaches for the U-boat fleet than their bases in Germany.

The plan of attack was for the British raiding force to sink two obsolete cruisers in the canal mouth at Ostend and three at Zeebrugge, thus preventing raiding ships leaving Bruges. The Ostend canal was the smaller and narrower of the two channels giving access to Bruges and so was considered a secondary target behind the Zeebrugge Raid. Consequently, fewer resources were provided to the force assaulting Ostend. While the attack at Zeebrugge garnered some limited success, the assault on Ostend was a complete failure. The German marines who defended the port had taken careful preparations and drove the British assault ships astray, forcing the abortion of the operation at the final stage.

Three weeks after the failure of the operation, a second attack was launched which proved more successful in sinking a blockship at the entrance to the canal but ultimately did not close off Bruges completely. Further plans to attack Ostend came to nothing during the summer of 1918, and the threat from Bruges would not be finally stopped until the last days of the war, when the town was liberated by Allied land forces.

Bruges

Bruges had been captured by the advancing German divisions during the Race for the Sea and had been rapidly identified as an important strategic asset by the German Navy. Bruges was situated inland at the centre of a network of canals which emptied into the sea at the small coastal towns of Zeebrugge and Ostend. This land barrier protected Bruges from bombardment by land or sea by all but the very largest calibre artillery and also secured it against raiding parties from the Royal Navy. Capitalising on the natural advantages of the port, the German Navy constructed extensive training and repair facilities at Bruges, equipped to provide support for several flotillas of destroyers, torpedo boats and U-boats.Messimer, p.57

By 1916, these raiding forces were causing serious concern in the Admiralty as the proximity of Bruges to the British coast, to the troopship lanes across the English Channel and for the U-boats, to the Western Approaches; the heaviest shipping lanes in the World at the time.Messimer, p.58 In the late spring of 1915, Admiral Reginald Bacon had attempted without success to destroy the lock gates at Ostend with monitors.Messimer, p.60 This effort failed, and Bruges became increasingly important in the Atlantic Campaign, which reached its height in 1917. By early 1918, the Admiralty was seeking ever more radical solutions to the problems raised by unrestricted submarine warfare, including instructing the "Allied Naval and Marine Forces" department to plan attacks on U-boat bases in Belgium.Snelling, p.200

The "Allied Naval and Marine Forces" was a newly formed department created with the purpose of conducting raids and operations along the coastline of German-held territory. The organisation was able to command extensive resources from both the Royal and French navies and was commanded by Admiral Roger Keyes and his deputy, Commodore Hubert Lynes. Keyes, Lynes and their staff began planning methods of neutralising Bruges in late 1917 and by April 1918 were ready to put their plans into operation.

Planning

To block Bruges, Keyes and Lynes decided to conduct two raids on the ports through which Bruges had access to the sea. Zeebrugge was to be attacked by a large force consisting of three blockships and numerous supporting warships. Ostend was faced by a similar but smaller force under immediate command of Lynes. The plan was for two obsolete cruisers— and —to be expended in blocking the canal which emptied at Ostend. These ships would be stripped to essential fittings and their lower holds and ballast filled with rubble and concrete. This would make them ideal barriers to access if sunk in the correct channel at the correct angle.Bennett, p.270

When the weather was right, the force would cross the English Channel in darkness and attack shortly after midnight to coincide with the Zeebrugge Raid a few miles up the coast. By co-ordinating their operations, the assault forces would stretch the German defenders and hopefully gain the element of surprise. Covering the Inshore Squadron would be heavy bombardment from an offshore squadron of monitors and destroyers as well as artillery support from Royal Marine artillery near Ypres in Allied-held Flanders. Closer support would be offered by several flotillas of motor launches, small torpedo boats and Coastal Motor Boats which would lay smoke screens to obscure the advancing blockships as well as evacuate the crews of the cruisers after they had blocked the channel.

British order of battle

Offshore Squadron

* ''Lord Clive''-class monitors with guns:
** , , and
* M15 class monitors with guns:
** , ,
* Destroyers:
** , and
** French Navy , and
* Light craft:
** 4 torpedo boats, 4 French motor launches

Inshore Squadron

* Blockships:
** ,
* Destroyers:
** , (destroyer leader), , , , ,
* Light craft:
** 18 Motor Launches, 8 Coastal Motor Boats

Artillery support was also provided by Royal Marine heavy artillery in Allied-held Flanders. The force was covered in the English Channel by seven light cruisers and 16 destroyers, none of which saw action.Ellis & Cox, p.223

Attack on Ostend

The assaults on Zeebrugge and Ostend were launched on 23 April, after being twice delayed by poor weather. The Ostend force arrived off