Kronprinzessin Cecilie, built at Stettin, Germany, in 1906 by Actien Gesellsehaft, was the last of a set four liners built for North German Lloyd, and the last German liner to carry four smokestacks. The liner was 19,400 GT (gross tonnage) and was 208.89 metres (685 ft 4 in) long by 22.00 metres (72 ft 2 in) abeam. She had four reciprocating, quadruple-expansion steam engines the powered four screw propellers. The Kronprinzessin sailed at a comfortable 23 knots (43 km/h).
The liner operated on North German Lloyd's Bremen – New York route, with occasional calls at other ports, including Boston, and New Orleans. While steaming toward Germany from America carrying some $2 million in gold bullion, she received word of the outbreak of war, headed back to the United States to avoid capture by the British Navy, and was interned at Bar Harbor, Maine. While at sea, her captain had ordered her funnels repainted as a form of disguise, so as to resemble the Olympic.
Commandeered by the United States 3 February 1917, the ship was transferred from the United States Shipping Board (USSB) to the U.S. Navy when America entered the war. She was renamed USS Mount Vernon, after George Washington's Virginia home. She was fitted out at Boston to carry troops and war materiel to Europe, and commissioned on 28 July 1917.