HMS Courageous was the lead ship of her class of three battlecruisers built for the Royal Navy in the First World War.

Designed to support the Baltic Project championed by First Sea Lord John Fisher, the ship was very lightly armoured and armed with only a few heavy guns.

She participated in the Second Battle of Heligoland Bight in November 1917 and was present when the German High Seas Fleet surrendered a year later.

She briefly became a training ship, but reverted to her normal role a few months before the start of the Second World War in September 1939.

In the First World War, Admiral Fisher was prevented from ordering an improved version of the preceding Renown-class battlecruisers by a wartime restriction that banned construction of ships larger than light cruisers in 1915.

At full capacity, she could steam for an estimated 6,000 nautical miles (11,110 km; 6,900 mi) at a speed of 20 knots (37 km/h; 23 mph).

Water had entered the submerged torpedo room and rivets had sheared in the angle irons securing the deck armour in place.

Admiral Beatty, the commander of the Grand Fleet, ordered most of his light cruisers and destroyers to sea in an effort to locate the enemy ships.

Courageous and Glorious were not initially included amongst them, but were sent to reinforce the 2nd Light Cruiser Squadron patrolling the central part of the North Sea later that day.

[15] Two German Brummer-class light cruisers managed to slip through the gaps between the British patrols and destroy a convoy bound for Norway on the morning of 17 October, but no word was received of the engagement until that afternoon.

The British continued in pursuit, but lost track of most of the smaller ships in the smoke and concentrated fire on the light cruisers.

[19] One fifteen-inch shell hit a gun shield of the light cruiser SMS Pillau but did not affect her speed.

At 9:30 the 1st Cruiser Squadron broke off their pursuit so that they would not enter a minefield marked on their maps; the ships turned south, playing no further role in the battle.

[20] After the battle, the mine fittings on Courageous were removed, and she spent the rest of the war intermittently patrolling the North Sea.

[24] The Washington Naval Treaty of 1922 severely limited capital ship tonnage, and the Royal Navy was forced to scrap many of its older battleships and battlecruisers.

[25] Her fifteen-inch turrets were placed into storage and reused in the Second World War for HMS Vanguard, the Royal Navy's last battleship.

[29] Courageous received a dual-purpose armament of sixteen QF 4.7-inch Mk VIII guns in single HA Mark XII mounts.

[30] In refits in the mid-1930s, Courageous received three quadruple Mk VII mounts for 40-millimetre (1.6 in) 2-pounder "pom-pom" anti-aircraft guns, two of which were transferred from the battleship Royal Sovereign.

[31] The reconstruction was completed on 21 February 1928, and the ship spent the next several months on trials and training before she was assigned to the Mediterranean Fleet to be based at Malta, in which she served from May 1928 to June 1930.

In the early 1930s, traverse arresting gear was installed and she received two hydraulic aircraft catapults on the upper flight deck before March 1934.

[38] In the early days of the war, hunter-killer groups were formed around the fleet's aircraft carriers to find and destroy U-boats.

Courageous departed Plymouth on the evening of 3 September 1939 for an anti-submarine patrol in the Western Approaches, escorted by four destroyers.

Two of the torpedoes struck the ship on her port side before any aircraft took off, knocking out all electrical power, and she capsized and sank in 20 minutes with the loss of 519 of her crew, including her captain.