Montclair was built in early 1918 as the British commercial refrigerated cargo ship S.S. War Speed for the civilian trans-Atlantic passenger service, the Cunard Line by the Standard Shipbuilding Corporation at Shooters Island, New York state.

On 19 August 1918, the United States Shipping Board took control of the Montclair from the British via the recently established wartime defense agency, the Emergency Fleet Corporation and moved the ship across the bay / New York Harbor to the east at the Brooklyn Navy Yard, on the East River in Brooklyn, New York City, and then immediately turned her over to the United States Navy, which then assigned her the naval registry identification number 3497 and commissioned her for defense / War duty that same day as the USS Montclair (ID-3497) for use 16 months after the United States declared war on the enemy Central Powers and entered the First World War (1914/1917-1918).

Montclair then departed Quiberon on 14 November 1918, three days after the Armistice for a westbound voyage back to America, but after weathering a gale she was forced to put in for repairs and fuel at the British islands colony off the East Coast of the North American continent at Bermuda.

In June 1919, the Montclair was directed to proceed to Galveston, Texas, on the northwest coast of the Gulf of Mexico to take on another cargo load, this time of onions, food destined for St. Nazaire.

Upon her arrival there on 25 June 1919 it was decided with the war over, to place her in line for demobilization from the U.S. Navy service and return to civilian commercial business purposes that she was originally designed and built for two years earlier.