Indefatigable owed her existence to political compromise. When a new Liberal government took power in January 1906 and demanded cuts to naval spending, the Admiralty lobbied for at least one battlecruiser to match Germany's expanding fleet. The Cabinet initially offered two obsolete armoured cruisers instead, but eventually relented. Indefatigable became the sole battlecruiser of the 1908-1909 Naval Programme -- a ship whose design was constrained from the start by cost. At 590 feet long and displacing 22,130 tons at deep load, she carried eight 12-inch guns in four twin turrets. Her wing turrets were staggered to allow some cross-deck firing, an improvement over earlier designs. A larger version with heavier armor and better underwater protection had been proposed but was rejected as too expensive. That rejection would prove fatal.

When war broke out in August 1914, Indefatigable was stationed in the Mediterranean with the 2nd Battlecruiser Squadron. Her first assignment was to hunt the German battlecruiser Goeben and the light cruiser Breslau, which had bombarded French Algeria and were racing eastward. What followed was a series of missed opportunities and confused orders that became one of the war's early embarrassments. Admiral Milne positioned his ships to block a westward breakout, but the Germans headed for Constantinople instead. Incorrect intelligence, contradictory Admiralty orders, and Milne's reluctance to believe the Germans were heading for the Dardanelles allowed Goeben and Breslau to escape. The ships' arrival in Turkey helped tip the Ottoman Empire into the war on Germany's side. Indefatigable bombarded Ottoman fortifications at the Dardanelles on November 3, 1914, then returned to British waters in February 1915 for North Sea patrol duty.

At Jutland, Indefatigable sailed as part of Rear Admiral Pakenham's 2nd Battlecruiser Squadron, the rearmost ships in Beatty's line. When the opposing battlecruiser forces opened fire at 15:48, the British were still completing their turn, and the German gunnery was accurate from the start. Indefatigable targeted Von der Tann, the last ship in the German line, but the British overestimated the range. Around 16:00, two or three German shells struck near her rear turret. She fell out of formation, sinking by the stern and listing to port. Then came the second volley -- a hit on the forecastle, another on the forward turret. Smoke and flames erupted from the bow, and massive fragments of the ship were hurled 200 feet into the air. Recent underwater archaeology has revealed that the initial hits detonated the rear magazine, snapping the ship in half. The supersonic shockwave from that explosion likely killed most of the crew instantly. The forward section drifted on under its own momentum before it too sank.

Three men survived. Able Seaman Frederick Elliott and Leading Signalman Charles Farmer found themselves in the water alongside their captain, C.F. Sowerby, who was badly wounded. A German torpedo boat rescued Elliott and Farmer, but Sowerby died of his injuries before they were pulled aboard. A third survivor, Signalman John Bowyer, was picked up by another German vessel. The Times initially misidentified him as belonging to a different ship. The two halves of Indefatigable's wreck lie separated on the North Sea floor -- the stern section was not discovered until recent surveys by nautical archaeologist Innes McCartney. The wreck, along with the other Jutland casualties, is now protected under the Protection of Military Remains Act 1986. In the Canadian Rockies, Mount Indefatigable was named for the battlecruiser in 1917 -- a granite monument on the far side of the world for the 1,016 men whose grave is the cold, dark water of the North Sea.