The ship's two quadruple-expansion steam engines turned her twin screw propellers that drove her at speeds of 13 to 14 knots (24 to 26 km/h; 15 to 16 mph).

Later that same year, Rhein served as a transport carrying German Empire troops as part of the Eight-Nation Alliance intended to put down the Boxer Rebellion in China.

She began what would become her last voyage for North German Lloyd on 16 July 1914 when she left Bremen bound for Baltimore, and was in that port when Germany declared war in early August.

After the United States declared war on Germany on 6 April 1917, Rhein, along with all other German ships interned in American ports, was seized by U.S. authorities.

Initially handed over to the United States Shipping Board (USSB), she was later transferred to the U.S. Navy to effect repairs caused by neglect and sabotage by her German crew.

The ship was overhauled, reconditioned, fitted out as a transport, and commissioned as USS Susquehanna at Norfolk, Virginia, on 5 September 1917.

Laid up in September 1922 after completing five roundtrips for United States Lines, the ship was sold in November 1928 to Japanese interests for scrapping.