 On 8 June 1917, her owner, Jeremiah Milbank of New York City, enrolled her in the Naval Coast Defense Reserve and the US Navy ordered her into service for use as a section patrol boat during World War I.She was commissioned as USS "Sapphire" (SP-710) on 14 September 1917 at Brooklyn, New York, with Ensign John S.(Seymour) Montgomery, USNRF, in command.After fitting out for naval service at Tebo's Yacht Basin, "Sapphire" joined the section patrol in the 3rd Naval District on 14 July 1918.