 On 28 April 1917, her officers and crew helped to put out a fire on the steam schooner "Rosalie Mahoney" in the St. Johns River in Florida.On 24 September 1917, "Isis" was transferred to the United States Navy for World War I service as the patrol vessel USS "Isis"

She was commissioned on 4 October 1917 with Lt. Gilbert T. Rude in command.After a minor overhaul, "Isis" commenced duty as the flagship for the Commander of Squadron 2 Cruiser Force, on 13 November 1917, at Staten Island, New York.