SS Kronprinzessin Cecilie was an ocean liner built in Stettin, Germany in 1906 for North German Lloyd that had the largest steam reciprocating machinery ever fitted in a ship at the time of construction.

After that country entered the war in April 1917, the ship was seized and turned over to the United States Navy, and renamed USS Mount Vernon (ID-4508).

In October 1919 Mount Vernon was turned over for operation by the Army Transport Service in its Pacific fleet based at Fort Mason in San Francisco.

USAT Mount Vernon was sent to Vladivostok, Russia to transport elements of the Czechoslovak Legion to Trieste, Italy and German prisoners of war to Hamburg, Germany.

[5] In what was a novelty at the time, first-class passengers in the dining saloon could choose à la carte dishes for no extra charge instead of being limited to a fixed menu.

[7] The liner operated on North German Lloyd's transatlantic route travelling from Bremen, with occasional calls at other ports, including Boston and New Orleans.

The ship was steaming toward Germany from America with Captain Charles Polack,[8] who had succeeded Dietrich Hogemann in 1913,[9] when she received word of the outbreak of war.

[10] The ship, bound for Bremen, was nearing Liverpool when directed to head back to the closest port in the neutral United States to avoid capture by the British Navy and French cruisers.

[10][11] Captain Polack had her normally all-buff funnels painted with black tops so as to resemble the liner Olympic or another ship of the British White Star Line as a form of disguise.

[10] North German Lloyd representatives met in Washington with officials of the departments of State, Treasury, Commerce and the United States Revenue Cutter Service (USRCS) with the result USRC Androscoggin was ordered to Bar Harbor to prevent unauthorized departure of foreign vessels but primarily to protect the transfer of gold and silver, as well as all mail and passengers, from Kronprinzessin Cecilie to shore to be transported by train to New York.

[2] Mount Vernon left New York for Brest on 31 October 1917 for her first U.S. Navy crossing, and during the war made nine successful voyages carrying American troops to fight in Europe.

Mount Vernon's officer of the deck promptly ordered right full rudder, but the ship could not turn in time to avoid the missile, which struck her amidships, knocking out half of her boilers, flooding the midsection, and killing 36 sailors and injuring 13.

[2] Mount Vernon rejoined the Cruiser and Transport Service in February 1919 and sailed on Washington's Birthday for France to begin returning veterans to the United States.

[14] USAT Mount Vernon made one trip between March and July 1920 to Vladivostok, Russia embarking elements of the Czechoslovak Legion to be disembarked at Trieste, Italy and 300 German prisoners of war for Hamburg, Germany.