"Gillis" was assigned as tender to Patrol Wing 4, Aircraft Scouting Force, U.S. Pacific Fleet. In the following months she performed plane guard patrol between San Diego and Seattle, Washington with time out for aircraft tending duties at Sitka, Alaska (14–17 June) ; Dutch Harbor and Kodiak (15–31 July). After overhaul in the Puget Sound Naval Shipyard she returned to Kodiak 16 October 1941 to resume tending of amphibious patrol planes in Alaskan waters. She was serving at Kodiak when the Japanese attacked Pearl Harbor and returned to the Puget Sound Naval Shipyard 9 February 1942 for overhaul.