Cairo entered service for the Egyptian Mail Steamship Company, a British-owned company that provided a fast mail service between Marseilles and Alexandria. The service was not successful and Cairo and sister ship Heliopolis were laid up in 1909 when the service ended. Both ships were sold to the newly established Toronto-based Canadian Northern Steamship Company, a subsidiary of the Canadian Northern Railway, in 1910, operating under its Royal Line brand. Cairo was renamed Royal Edward, HeliopolisRoyal George, and they were refitted for the North Atlantic. Royal Edward sailed from Avonmouth to Montrealin the summer and to Halifax in the winter. At the outbreak of World War IRoyal Edward and Royal George were requisitioned for use as troopships.
World War I
Royal Edward was used to bring Canadian troops to Europe before being used as an internment ship anchored of Southend-on-Sea. On 28 July 1915, Royal Edward embarked 1,367 officers and men at Avonmouth. The majority were reinforcements for the British 29th Infantry Division, with members of the Royal Army Medical Corps. All were destined for Gallipoli. Royal Edward was reported off the Lizard on the evening of 28 July, and had arrived at Alexandria on 10 August, a day after sister ship Royal George had sailed from Devonport. Royal Edward sailed for Moudros on the island of Lemnos, a staging point for the Dardanelles. On the morning of13 August, Royal Edward passed the British hospital ship, heading in the opposite direction. Oberleutnant zur SeeHeino von Heimburg in the German submarine was off the island of Kandeloussa and saw both ships. He allowed Soudan to pass unmolested, and focused his attention on the unescorted Royal Edward some off Kandelioussa. He launched one of UB-14s two torpedoes from about away and hit Royal Edward in the stern. She sank by the stern within six minutes. Royal Edward was able to get off an SOS before losing power, and Soudan arrived on the scene at 10:00 after making a 180° turn and rescued 440 men in six hours. Two French destroyers and some trawlers rescued another 221. According to authors James Wise and Scott Baron, Royal Edwards death toll was 935 and was high because Royal Edward had just completed a boat drill and the majority of the men were below decks re-stowing their equipment. Other sources report different numbers of casualties, from 132 to 1,386 or 1,865. An Admiralty casualty list, published in The Times in September 1915, named 13 officers and 851 troops as missing believed drowned, a total of 864 lost, including posthumous Victoria Cross recipientCuthbert Bromley and footballer Walter Miller.