Built Devonport Dockyard, laid down February 1909, completed April 1911, cost £1,520,591.
Length 588 feet waterline 590 feet overall, beam 79 feet 10 inches, draught 30 feet, displacement 18,750 load 22,080 tons deep.
4 shaft Parsons turbines, 44,000 shp, 25kts
Indefatigable 55,140 shp = 26.89 knots
6-4in belt, 7in barbettes, 7in turret faces, 2.5-1in decks
8 x 12in 45cal MK X (4 x 2), 16 x 4in (16 x 1), 3 x 18in TT
HMS Indefatigable was commissioned in February 1911 and joined the 1st Cruiser squadron (renamed in 1913 as the 1st Battle Cruiser Squadron. She joined the 2nd Battle Cruisers squadron in the Mediterranean and at the outbreak of World War one in August took part in the pursuit of Goeben and Breslau and also bombarded Cape Helles. She became the Flagship of Admiral Carden in November 1914 until January 1915. After a refit at Malta she joined the The Grand Fleet as part of the 2nd Battle Cruiser Squadron and was sunk at The Battle of Jutland by 11 inch shell fire from Van Der Tann. Official reports state she was hit by two shells in the X magazine causing her to stagger out of formation sinking by the stern this was followed by another hit on the foredeck causing a much more larger explosion which destroyed her. She sank so quickly that only 2 crew could be rescued.