The U.S. Navy acquired Lydonia II from Lydon on 21 August 1917 for use as a patrol vessel during World War I. Slightly modifying her name, the Navy commissioned her as USS Lydonia (SP-700) on 27 October 1917 with Lieutenant Commander R. P. McCullough in command.
After repairs and target practice off Bermuda, Lydonia departed the Caribbean in mid-November 1917 and arrived at Horta in the Azores on 7 December 1917.