The
United States Department of War acquired
Mexican for
World War I service on a
bareboat charter basis on 10 December 1917. On 23 December 1917, the Department of War transferred
Mexican to the U.S. Navy, which gave her the naval registry Identification Number (Id. No.) 1655 and
commissioned her the same day as USS
Mexican. Manned by U.S. Navy personnel and operated on a
United States Army account,
Mexican was assigned to the
Naval Overseas Transportation Service and served as an
animal transport through the end of World War I.
Mexican was in port at
St. Nazaire,
France on 13 May 1918 when a fire broke out aboard her. Lookouts aboard the cargo ship
USS Alaskan (ID-4542), lying directly astern of
Mexican, spotted the fire breaking out.
Alaskan called away her fire and
rescue party, which aided
Mexican's men in controlling the blaze before it did serious damage. On 13 December 1918,
Mexican was transferred to the
Cruiser and Transport Force for use as a troop transport. Refitted for that purpose by the U.S. Army, she steamed on round-trip voyages from the
United States East Coast to
Europe for several months in 1919, bringing American troops who had completed their war service in
Europe home to the
United States. The Navy returned
Mexican to the American-Hawaiian Steamship Company on 4 August 1919. She returned to commercial service as SS
Mexican. ==World War II==