RMS Atrato a.k.a. HMS Viknor
When the UK entered the First World War in 1914 the Admiralty requisitioned her, had her re-fitted as an armed merchant cruiser and commissioned her as HMS Viknor. She was placed under the command of Commander EO Ballantyne with a complement of 22 officers and 273 ratings and assigned to the 10th Cruiser Squadron.
On 28 December 1914 Viknor went on patrol from the River Tyne, and on 1 January she joined "B" patrol off the north coast of Scotland. The patrol was ordered to find and stop the neutral Norwegian America Line ship Bergensfjord, which the UK Government believed was carrying a suspected German spy. Viknor found Bergensfjord, detained her and escorted her to Kirkwall in Orkney. There the suspect and a number of other prisoners were transferred to Viknor, which then left for Liverpool.
Viknor never reached her destination. On 13 January 1915 she sank with all hands in heavy seas off Tory Island, County Donegal, Ireland.