Following the attack on Pearl Harbor, "Sailfish" departed Manila on her first war patrol, destined for the west coast of Luzon. Early on 10 December, she sighted a landing force, supported by cruisers and destroyers, but could not gain firing position. On the night of 13 December, she made contact with two Japanese destroyers and began a submerged attack; the destroyers detected her, dropping several depth charges, while "Sailfish" fired two torpedoes. Despite a large explosion nearby, no damage was done, and the destroyers counterattacked with 18–20 depth charges. She returned to Manila on 17 December.