Some of the Company’s largest and fastest M-Class ships were hastily requisitioned as Armed Merchant Cruisers (AMC). On the 4th August 1914 MANTUA returned to Tilbury after a pleasure voyage to Norway and Copenhagen. In an abrupt end to peace and P&O’s summer cruise schedule, MANTUA was fitted with eight 4.7” guns before joining the 10th Cruiser Squadron on the Northern patrols.
With their speed and size, the M-Class cruisers helped maintain blockade lines and provided armed escorts for convoys. After America entered the war in 1917, many of the Company’s AMCs were used as troop and transport ships on the Atlantic. MOLDAVIA was carrying troops of the 28th Regiment of US Army from Halifax, Nova Scotia in May 1918 when she was torpedoed and sunk by a German U-boat off Beachy Head, in striking distance of the English coast.