Originally laid down as Minnelora on 7 June 1902 in Shipway J at New York Shipbuilding in Camden, New Jersey for the Atlantic Transport Line, she was purchased by E. H. Harriman's Pacific Mail Steamship Co. for its San Francisco-Far East service, and renamed Mongolia.

In early August 1915, Pacific Mail announced it could not affordably meet the language clause of the Seamen's Act in the Far East and intended to cease commercial shipping operations there.

[11] Later that month, the company sold five of its liners, including Mongolia, to Atlantic Transport Line, for whom she plied the New York-London route.

One month later, Mongolia became the first American vessel to test the blockade, using those guns to drive off (and possibly sink) a U-boat seven miles southeast of Beachy Head, in the English Channel.

During the afternoon of 20 May 1917, the nurses were on the deck of the Mongolia, observing the firing of the aft 6-inch gun, when they were struck by fragments of the shell's brass casing.