On 6 April 1917 the US entered the First World War, and on 1 June the Navy Department bought Remlik for conversion into a patrol craft.

On 10 June she was delivered to the US Navy, and the next day she was commissioned, with the pennant number SP-157 and code letters GSLK.

[5] Her first commander in naval service was Lt Cdr Isaac C Johnson Jr.[3] Remlik crossed the Atlantic to France, where she undertook anti-submarine and coastal patrols in the Bay of Biscay.

[3] The heavy sea washed overboard the depth charge box attached to Remlik's taffrail.

But the Sperry depth charge fell inboard, lost its safety pin, and began to roll around on deck.

Chief Boatswain's Mate John MacKenzie, USNRF ran to the depth charge, and sat on it to keep it from moving, enabling his shipmates to lash it securely to the deck.

[3] Remlik continued her patrol service, and escorted ships along the French coast, until the end of the First World War.