Gato-Class Wins WWII! 1941 – Suddenly the war in the Pacific was a reality. The need for ocean-going fleet boat capability was now a necessity. There were 73 Gato class submarines built in 1942 and 1943. Their main task was to carry out offensive action against enemy shipping. They are credited with winning the war in the Pacific, accounting for more than half the total Japanese tonnage sunk. The Gato-class, with its dual engine rooms, large fuel capacity, 10 torpedo tubes, deeper diving (400 feet) and surface speed of 21 knots, was the answer!