HMS Indefatigable joined the 2nd Battle Cruisers Squadron in the Mediterranean and after the outbreak of WW1, 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 Grand Fleet.

She was sunk at Jutland by 11 inch shell fire from the German Battlecruiser SMS Van Der Tann.

Official reports state she was hit by two shells in the "X" magazine, blowing out her bottom, and causing her to stagger out of formation, sinking by the stern. Following another hit on the foredeck in the area of "A" turret, the forward magazine exploded, she sank quickly killing all but four of her crew.