Today, two monitor classes that served during WWII.
Two ships of the Erebus class were built by Harland & Wolff in 1915-1916. Named for the two bomb ketches sent to investigate the Northwest Passage and subsequently lost in 1845, HMS Erebus and Terror were designed as stable gun platforms with a shallow draft to allow operations close inshore in support of land operations and were not intended to contest naval battles. The Erebus class were designed to outrange German World War I heavy shore batteries and they were also fitted with highly effective anti-torpedo bulges on each side of the hull.
During World War I Erebus bombarded German naval forces based at the Belgian ports of Ostend and Zeebrugge. On 28 October 1917, she was damaged by a remote controlled German FL-boat, and suffered the loss of 50 feet (15 m) of anti-torpedo bulge. In 1919 Erebus took part in the British Invasion of Russia providing gunfire support in the White Sea and in the Baltic Sea. In 1921 Erebus took part in gunnery trials against the surrendered German battleship Baden. She then served as a gunnery training ship between the two world wars. The Erebus had a refit, completed in August 1939, and was earmarked as guardship at Cape Town, but due to the outbreak of war this never materialised.
In the early war years, Erebus served with the Eastern Fleet and the Mediterranean Fleet, where she was used to run supplies to besieged Tobruk and bombard enemy concentrations. In 1943 she was damaged while bombarding Sicily during the Allied invasion of Sicily.
Erebus was used for coastal bombardment during the Normandy Landings on 6 June 1944, firing at the batteries at Barfleur and La Pernelle. She suffered one 15-inch gun destroyed due to a premature explosion of the HE round in the bore. On the 10 August 1944, she was used against the defenders of the harbour at Le Havre. She was damaged by the battery at Clos des Ronces and was out of action for some time. In November 1944, she supported Operation Infatuate, the amphibious assault on Walcheren, Netherlands.
HMS Terror joined the Dover Patrol in August 1916 and operated against German forces on the coast of occupied Belgium. On 19 October 1917, she was torpedoed by German motor torpedo boats off Dunkirk. There were no casualties and the ship was beached before being towed back to Portsmouth. The damage took three months to repair. In April 1918, Terror was in the Long Range Bombardment force for Zeebrugge raid with her sister ship Erebus and destroyers Termanent, Truculent, and Manley. On 27 September, Terror, along with her sister ship Erebus, provided gunnery support for the Fourth Battle of Ypres. In the early 1920s, she was used for gunnery trials against several old warships including Baden and Superb.
At the outbreak of war in 1939, Terror was based at Singapore, supporting the defences of the major naval base there, and had to be recalled to serve in theatres closer to home. She mainly served in the Mediterranean Theatre during the Second World War. After first using her anti-aircraft armament to help defend Malta against the first Italian Regia Aeronautica air attacks on 11 June 1940, Terror played an important part in Operation Compass, the British assault against the Italian Tenth Army in Libya.
During the successful advance by the Western Desert Force (later to become the 8th Army "Desert Rats"), Terror bombarded Italian land forces and fortifications, amongst others the fortified port of Bardia in eastern Libya, firing 660 rounds from her main guns. The ship also served as a water carrier for the advancing British and Commonwealth army. Terror was subjected to diving attacks by German Junkers Ju 88 bombers on 22 February 1941 after leaving Benghazi. She was badly damaged by near misses and abandoned by her crew. Although taken under tow, she sank off Darnah, Libya before reaching the Royal Navy's Mediterranean Fleet base at Alexandria, Egypt.
The Roberts class of monitors of the Royal Navy consisted of two heavily-gunned vessels built during the Second World War. They were the Roberts, completed in 1941, and Abercrombie, completed in 1943.
HMS Roberts provided bombardment support during Operation Torch in North Africa, where she was damaged by two 500 kg bombs. She was repaired in time to support Operation Husky (the invasion of Sicily), Allied landings near Salerno Operation Avalanche, the D-Day landings and the Walcheren operations.
HMS Roberts was sold for scrapping shortly after the war, but hired back by the navy as an accommodation ship at Devonport until 1965. She was broken up at Inverkeithing in July 1965.
HMS Abercrombie was built by Vickers Armstrong, Tyne. She was laid down 26 April 1941, launched 31 March 1942 and completed 5 May 1943. She used a 15-inch gun turret originally built as a spare for HMS Furious. On completion, HMS Abercrombie deployed to the Mediterranean and in July 1943, she provided support to the Operation Husky (the invasion of Sicily).
On 9 September 1943, HMS Abercrombie was supporting the Allied landings near Salerno (Operation Avalanche), when she was damaged by a contact mine. She was repaired at the dockyard at Taranto in October and on completion, HMS Abercombie arrived at Malta on 15 August 1944. On 21 August 1944, whilst on an exercise south-east of Malta, she struck two mines and was again damaged.
On completion of repairs, HMS Abercrombie was despatched to the Pacific, but the war ended before she could arrive there. The ship returned to Chatham in November 1945 where she was used for Gunnery training and also as an Accommodation Ship until 1954. She was scrapped at Barrow beginning 24 December 1954.