 The British government, via the Ministry of War Transport (MoWT), also had new ships built during the course of the war, these being known as Empire ships.In addition to its existing merchant fleet, United States shipyards built 2,710 Liberty ships totalling 38.5 million tons, vastly exceeding the 14 million tons of shipping the German U-boats were able to sink during the war.Canada's Merchant Navy was vital to the Allied cause during World War II.