(Main articles: List of ships of the Royal Canadian Navy and History of the Royal Canadian Navy) With the outbreak of war, Great Britain and Canada planned to significantly expand the RCN. Government and commercial vessels were pressed into naval service, vessels were transferred, loaned or purchased from the Royal Navy, and many smaller vessels were constructed in Canada. The List of Royal Canadian Navy ships of the First World War lists the surface warships, submarines and auxiliary vessels in service during the war. It includes all commissioned, non-commissioned, loaned or hired ships. and all ships crewed by RCN personnel under the command of the RCN.