credited with having destroyed either. Apogon ended her patrol after 50 days and returned to Pearl Harbor on 9 March. Apogon moored beside on 10 March to commence refit. The submarine was drydocked at the Pearl Harbor Navy Yard from 15 to 19 March for the installation of two new propellers. After additional training exercises, she got underway on 2 April. She paused at Johnston Island on 4 April to refuel, and later that day resumed her voyage toward waters south of the Japanese home islands. However, when a crewman was preparing to clean a 20 millimeter machine gun the next day, a live cartridge accidentally left in the chamber discharged and ricocheted into the man's leg. Apogon immediately returned to Johnston Island to transfer the wounded man to the dispensary. The submarine again got underway on 6 April and conducted her entire patrol without encountering any enemy shipping. She finally arrived at Majuro on 22 May. Refitting began on 23 May, and the submarine got underway on 8 June for trials. Apogon began her fourth patrol, which was in the area between Formosa and the Philippines, in company with , , and . On 12 July, Apogon and her wolf pack consorts spotted a nine-ship Japanese convoy sailing with approximately six escorts. The submarines immediately began preparing an attack. The leading Japanese ship of the center column of the formation apparently sighted the wake of Apogon'''s periscope and turned back to ram the submarine. As Apogon was turning to port to bring her stern tubes to bear, she was struck on the starboard side by the freighter. About eight feet of the main periscope and periscope shears were torn off, and the radar masts were bent and put out of commission. As a result, Apogon prematurely ended her patrol to return for repairs. She arrived at Midway on 22 July, where crews installed additional bracing on the periscope shears before the submarine proceeded on to Pearl Harbor. Having reached Pearl Harbor on 26 July, Apogon was dry-docked. Both tail shafts were replaced and realigned, and the periscope, periscope shears, and the radar masts were replaced. The three main engines were also overhauled. On 12 September, Apogon was underway on yet another wartime patrol. She headed for the Kuril Islands area. The submarine then sunk a Japanese patrol craft on 23 September the 400 ton Choyo Maru No.6. Four days