Built by Fairfield Shipbuilding and launched on the 13th May 1911, Gloucester Castle was the third of the second "G" class.
She was requisitioned in September 1914 and converted to a hospital ship. In this capacity she served from 9th september 1914 until 9th September 1919.
On 31st March 1917 she was torpedoed by the german submarine UB32 whils on service in the English Channel. She survived and was towed to Portsmouth.
She was demobilised in 1920 and returned to the Intermediate Route.
She remained inservice for another 22 years. On the 15th July 1942 she was attacked and sunk by the German raider MICHEL 750 miles from Ascension Island with the loss of 93 lives.