On 6 March 1915 "Trent" was requisitioned as a depot ship by the Admiralty and assigned to support the river monitors , and during the Gallipoli campaign. "Trent" was used to transport the monitors' crews to Malta, while the monitors themselves were towed there by tugs. "Trent" continued to be used in support of the monitors, accompanying "Mersey" and "Severn" to East Africa in July 1915, for their attack on the on the Rufiji River. "Trent" later returned to British waters, on 1 October 1917 became the depot ship for HMS "Icarus", the Royal Naval Air Service base at Houton Bay, Scapa Flow. Here she supported the Orkney Air Service's anti-submarine patrols until March 1918. "Trent" was returned to the Royal Mail Steam Packet Company shortly after the end of the war, on 23 January 1919. She was broken up at Rotterdam in February 1922.