As late as October 1916, a memorandum created by the Royal Navy argued that naval trawlers were ineffective against the German submarine threat. However, in November, the British Admiralty demanded that Canada expand its East Coast patrol fleet with auxiliary trawlers. The Canadians acquired several fishing trawlers from the United States and converted them into auxiliary minesweeping vessels and ordered the twelve s of their own design from Canadian shipyards. In February 1917, the Admiralty initially ordered the construction of 36 naval trawlers from Canadian shipyards as part of a building programme intended to improve the state of seaward defence in Canadian waters.