She next proceeded with Task Unit 51.14.3 for the invasion of Okinawa and rendered invaluable service to battle- and weather-damaged destroyers, landing craft and patrol vessels.

This heroic action is credited as having saved the lives of the Endymion's crew, because common practice was for Japanese naval commanders to sink damaged ships and leave no survivors.

Cannon fire from the twin 20mm guns is thought to have severely damaged and possibly penetrated the conning tower, forcing the Japanese submarine to submerge and run.

However, Endymion sat immobile for two to three days, during which time crew reported seeing a US Navy sea plane (Martin PBM-5 Mariner) approach, circle, turn around, and fly off.

She continued to Pearl Harbor where she readied herself for return to take part in the invasion of Japan, but the war ended and Endymion headed back to the United States.