Dreadnaught was assigned to Patrol Force, United States Atlantic Fleet, and departed New London on 25 April 1918 to escort a convoy of submarine chasers to the Azores.

On 24 October 1918, she departed New London with a third convoy to the Azores, then proceeded to Brest, France, as escort for the United States Army tug Cuba.

Dreadnaught should not be confused with the patrol vessel USS Dreadnought (SP-584), which also was in commission during World War I. Dreadnaught operated on harbor duty at Brest and towed barges and ships between Brest, Lorient, and Bordeaux, France, until 20 March 1919, when she got underway to escort a convoy of submarine chasers to Lisbon, Portugal, and then on to Bermuda.

Dreadnaught left Norfolk on 23 January 1920 bound for the Mare Island Navy Yard in Vallejo, California, where she arrived on 15 March 1920 and began another overhaul.

On 14 March 1922, Dreadnaught was decommissioned, but she continued her 12th Naval District duties in the San Francisco area for many years after that in a non-commissioned "in-service" status.