HMS Mersey

HMS Mersey was a Humber class monitor that served off the coast of Belgium and the east coast of Africa during the First World War. She was purchased by Britain at the start of the war, having been built for Brazil. She saw service off the Belgian coast during October-November 1914, taking part in the race to the sea and the battle of the Yser.

By the end of those operations her original 6in guns were worn out. The turret was replaced by one 6in BL Mk VII gun at each end of the ship, with the howitzers moved from the quarterdeck to the boat deck. All three were sent to Malta in March 1915. Originally she was to be sent to the Dardanelles, but soon after she reached Malta it was decided to send HMS Mersey and HMS Severn to the east coast of Africa, to take part in operations against the German cruiser Königsberg. She was hiding in the shallow Rufiji delta, beyond the reach of British cruisers. The two monitors left Malta on 28 April, reached Aden on 15 May and Mafia Island on 3 June, after a very difficult journey. On occasions the entire squadron had to act as tugs for the monitors. 

The next month was spent repairing damage sustained during the journey, and fitting extra side and deck armour to the monitors. They were finally ready on 5 July, and at 5.20am on 6 July entered the Kikunka mouth of the Rufiji. The first day's bombardment was not a great success. The two ships took position 11,000 yards from the Königsberg, and came under immediate accurate fire. After an hour the Severn was hit and forced to retreat, although returned to the fight later in the day. When the bombardment ended at 3.30, the two monitors had fired 635 shells, but had only scored 6 recorded hits.

The next attempt was made on 11 July. This time HMS Mersey docked at the first day’s firing position, while the Severn moved a mile further up the river before opening fire at 12.30pm. Her eighth shell hit the Königsberg. A large explosion was noted at 12.52 and the battle was over by 2.30. HMS Mersey suffered two casualties, both wounded, during the battle.

The two ships remained in East Africa after sinking the Königsberg, as part of the East Africa Group. HMS Mersey was towed back to the Mediterranean between March and May 1918. In October 1918 all three Humber class monitors were reunited at Mudros, sailing through the Dardanelles after the Turkish surrender. The Mersey spent a few months operating in the Black Sea and on the Danube, before returning to Britain in May 1919.

Next time, 11 July (after repairs), Mersey anchored at first days firing point, Severn sailed on to 12.30, makes another mile, then opend fire, hit with 8th salvo, 12.52 large explosion on K, fight over by 2.30

Displacement (loaded)


Top Speed




Armour – belt


 - bulkheads


 - barbette


 - turret face



266ft 9in

Armaments as built

Two 6in guns
Two 4.7in howitzers
Four 3pdr guns
Six 7mm Hotchkiss machine guns

Crew complement



30 September 1913


February 1914

Sold for break up



Lt. Commander R. A. Wilson
Lt. Commander Garbett

Books on the First World War | Subject Index: First World War

How to cite this article: Rickard, J (26 October 2007), HMS Mersey ,

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