Orduna was requisitioned as an auxiliary cruiser and troop transport in the First World War running from Halifax, Canada to Liverpool with notables such as Quentin Roosevelt on board. In January 1915 Orduna rescued the Russian crew of the sailing ship Loch Torridon, which had sprung a leak while transporting timber off the west coast of Ireland. Later in July 1915, en route to New York City, Orduna was targeted by a U-boat. The torpedo, which was spotted by Captain Taylor, missed the ship, which arrived safely. In 1918 Orduna collided with the 4,406-ton steamer Konakry, carrying a cargo of ballast from Queenstown to Trinidad. Konakry was lost in the accident.
Between the wars
In April 1923 she was involved in another rescue, transporting the crew of the barquentineClitha, which had been abandoned and set on fire, to England after they had been rescued by the schoonerJean Campbell. In 1925, Dean James E. Lough of the Extra-Mural Division of the New York University chartered Orduna for the transport of 213 students to France, with lectures taking place on board. In 1938 the Orduna was used for the third and final 'Peace Cruise', carrying 460 Scouters and Guiders, including Robert and Olave Baden-Powell, and their daughter Heather, on a cruise to Iceland, Norway, Denmark and Belgium. Orduna left Liverpool on 8 August, returning on 25 August via Dover. Robert Baden-Powell was too ill to leave the ship during the voyage, but parties of local Scouts visited him on the ship at most of the stops, while the Scouters and Guiders on the ship took the opportunity to tour local landmarks and attend receptions. During the stop at Reykjavík on Thursday, 11 August, during which Orduna moored beside the German cruiser Emden, a party from the Scouts of Iceland brought some rock on board so that Baden-Powell could still 'set foot in Iceland'. The Orduna called at Trondheim, Norway, on 15 August, Copenhagen, Denmark on 18 August, and Belgium on Sunday 21 August, before returning to England. In September 1938 she was at Nassau, Bahamas and Kingston, Jamaica
During the 1939 "Voyage of the Damned" affair, where German Jewish refugees were refused entry into Cuba, the United States and Canada, Orduna was refused permission to land 40 refugees at Havana. On 12 August 1940, she sailed from Liverpool arriving Nassau 30 August, with a privately organised party of 16 children from Belmont Preparatory school, Hassocks Sussex. It was part of a wider Government children's evacuation programme Children's Overseas Reception Board during World War II. When the prospect of imminent invasion threatened Britain. With the need for military transport in the Second World War, in 1941 she was put into service by the British government as a troopship. Another task during the Second World War was that of an evacuation transport. In the autumn of 1945 the Orduña brought back Prisoners of War and internees from the Far East, landing at Princess Landing Stage in Liverpool on 19 October. A memorial to the ships involved in the repatriation was unveiled on the Liverpool waterfront on 15 October 2011.
Post-Second World War
In 1947 conditions for troops returning from Port Said in Egypt on the Orduna, said to include overcrowding and poor food, were raised with the Secretary of State for War.
Demise
Orduna was decommissioned and laid up in November 1950 and dismantled the following year in Dalmuir, Scotland.
