China Sea. On the second night in her assigned patrol area, Spot expended all torpedoes attacking a Japanese convoy. They sank the passenger-cargo ship, Nanking Maru, and damaged a freighter. The attack was made in heavy weather and shallow water. Spot was surfaced and heading for deeper water but could not elude one of the escorts, the minesweeper W-17, which closed to and opened fire. Spot manned her guns and returned the fire even though she was wallowing heavily in the rough seas. A lucky hit by her gun knocked out W-17's forward gun and saved the submarine from almost certain disaster. Spot secured her guns, cleared the bridge, and submerged. The escort dropped a few depth charge patterns which caused no damage, and the submarine returned to Saipan on 23 March to reload. On 27 March 1945, Spot resumed her patrol. On 31 March 1945, she was on the surface in the Philippine Sea southeast of Kagoshima, Kyushu, Japan at when she sighted a destroyer that offered no recognition signals. Spot maneuvered to close when the destroyer turned towards her and increased its speed. When the range was approximately , the destroyer opened fire. Spot fired a recognition flare that the destroyer answered with a second salvo. As Spot submerged, another salvo straddled her conning tower. After Spot reached a depth of , she and the destroyer exchanged recognition signals and the destrover discontinued its attack. The destroyer was later identified as , which reported firing fifteen rounds. Spot suffered no damage or casualties in this friendly fire incident. Third and fourth war patrols, April – July 1945 During the first week of April, Spot guarded the approaches to Kii Suido. After aircraft from the Fast Carrier Task Force sank battleship Yamato, a cruiser, and four destroyers in the East China Sea on 7 April, the submarine patrolled in that area. She hunted off the China coast and then conducted a reconnaissance of Kokuzan To, off Korea and decided to shell a radio station on the northwest tip of the island. On the evening of 25 April, she surfaced and began the bombardment which hit an oil storage area, several barracks, and set the radio station on fire. Spot returned to the Mariana Islands on 4 May for refit. Spot began her last war patrol on 2 June and performed lifeguard services off the coast of Honshū until 23