HMS Colossus was the lead ship of her class of two dreadnought battleships built for the Royal Navy at the end of the first decade of the 20th century.

Aside from participating in the Battle of Jutland in May 1916 and the inconclusive action of 19 August, her service during World War I generally consisted of routine patrols and training in the North Sea.

Colossus was the only dreadnought from the main body of the Grand Fleet to be hit during the Battle of Jutland, although she suffered only minor damage.

The design of the Colossus class was derived from that of the earlier HMS Neptune with redistributed armour and more powerful torpedoes.

The turbines were rated at 25,000 shp (19,000 kW) and were intended to give the ship a maximum speed of 21 knots (39 km/h; 24 mph).

[3] During her full-power, eight-hour sea trials on 30 March 1911, she reached a top speed of 21.6 knots (40.0 km/h; 24.9 mph) from 29,296 shp (21,846 kW) in a moderate storm.

The Colossus-class ships carried enough coal and fuel oil to give them a range of 6,680 nautical miles (12,370 km; 7,690 mi) at a cruising speed of 10 knots (19 km/h; 12 mph).

[3] They had a waterline belt of Krupp cemented armour that was 11 inches (279 mm) thick between the fore and aftmost barbettes that did not cover the full length of the ships.

In addition, some machinery was removed during the refit to render her non-combat worthy in accordance with the Washington Naval Treaty.

During this time, she conducted gunnery practice off Portland at a range of 14,000 yards (13,000 m), the longest shoot performed by any ship of the RN before the start of the war.

On the evening of 22 November 1914, the Grand Fleet conducted a fruitless sweep in the southern half of the North Sea; Colossus stood with the main body in support of Vice-Admiral David Beatty's 1st Battlecruiser Squadron.

[18] Jellicoe's ships, including Colossus, conducted gunnery drills on 10–13 January 1915 west of Orkney and Shetland.

On 2–5 September, the fleet went on another cruise in the northern end of the North Sea and conducted gunnery drills.

On the night of 25 March, Colossus and the rest of the fleet sailed from Scapa Flow to support Beatty's battlecruisers and other light forces raiding the German Zeppelin base at Tondern.

On 21 April, the Grand Fleet conducted a demonstration off Horns Reef to distract the Germans while the Imperial Russian Navy relaid its defensive minefields in the Baltic Sea.

[1] During the first stage of the general engagement, the ship fired three salvos from her main guns at a barely visible battleship at 18:30.

The destroyer was not hit, but the detonations of the near misses caused her condensers to spring leaks, which gradually reduced her speed.

[26] About 19:15, she engaged the battlecruiser SMS Derfflinger at a range of only 8,000–9,000 yards (7,300–8,200 m) with five salvos of armour-piercing, capped (APC) shells.

In return she was struck by two shells fired by the battlecruiser SMS Seydlitz at 19:16, but neither caused any significant damage, splinters igniting a few 4-inch propellant charges that were easily put out.

They enforced strict wireless silence during the operation, which prevented Room 40 cryptanalysts from warning the new commander of the Grand Fleet, Admiral Beatty.

The British only learned of the operation after an accident aboard the battlecruiser SMS Moltke forced her to break radio silence to inform the German commander of her condition.

On 30 June 1921, she was listed for disposal, but become a boys' training ship in September, and was refitted to suit her new role.

Colossus was withdrawn from the disposal list on 23 July 1923 and hulked for the use of the training establishment HMS Impregnable at Devonport.