HMS Inflexible was one of three Invincible-class battlecruisers built for the Royal Navy before World War I and had an active career during the war. She tried to hunt down the German battlecruiser SMS Goeben and the light cruiser SMS Breslau in the Mediterranean Sea when war broke out and she and her sister ship Invincible sank the German armoured cruisers SMS Scharnhorst and SMS Gneisenau during the Battle of the Falkland Islands. Inflexible bombarded Turkish forts in the Dardanelles in 1915, but was damaged by return fire and struck a mine while maneuvering. She had to be beached to prevent her from sinking, but she was patched up and sent to Malta, and then Gibraltar for more permanent repairs. Transferred to the Grand Fleet afterwards, she damaged the German battlecruiser Lützow during the Battle of Jutland in 1916 and watched Invincible explode. She was deemed obsolete after the war and was sold for scrap in 1921.

The three Invincible-class battlecruisers were built for the Royal Navy and entered service in 1908 as the world's first battlecruisers. They were the brainchild of Admiral Sir John ("Jacky") Fisher, the man who had sponsored the construction of the world's first "all-big-gun" warship, HMS Dreadnought. He visualised a new breed of warship, somewhere between the armoured cruiser and battleship; it would have the armament of the latter, but the high speed of the former. This combination would allow it to chase down most ships, while allowing it to run from more powerful designs.