USS Mercury (ID-3012) was a United States Navy transport ship during World War I.

[1] At the outset of World War I the ship was interned by the United States and, when that country entered the conflict in 1917, was seized and converted to a troop transport.

SS Barbarossa was built by Blohm & Voss, Hamburg, Germany, in 1896, for the North German Lloyd Line.

[2] With the outbreak of World War I, she took refuge in Hoboken, New Jersey, and was interned by the United States.

After the armistice, she reversed the flow of troops, making eight crossings to return more than 20,000 to the United States.