On 5 March, "Tullibee" stood out of Pearl Harbor to begin her fourth war patrol. Nine days later, she called at Midway Island to top off her fuel and then proceeded to her patrol area in the Palau Islands. She was scheduled to support aircraft carrier strikes against those islands on 30–31 March. On 25 March, "Tullibee" arrived on station and began patrolling. The next day, off the Palau Islands she made radar contact on a convoy consisting of a large passenger-cargo ship, two medium-sized freighters, a destroyer, and two other escorts. The submarine made several surface runs on the transport but kept losing her in rain squalls. "Tullibee" finally closed to and launched two torpedoes from her bow tubes at the target. About two minutes later, the submarine was rocked by a violent explosion. It was only learned after the war that "Tullibee"s torpedo had run a circular course and she had sunk herself.