The Yamato and its lesser-known sister-ship Musashi were designed in the 1930s to take on American battleships in a climactic duel for control of the Pacific. Neither vessel ever saw a US Navy battleship, but by the time they were committed in the final battles of 1944–45, both would face overwhelming American naval air power. By 1944, the US Navy had combined its rugged Avenger torpedo-bombers with an improved air-launched weapon to create a formidable ship-killing capability. Augmenting the Avengers was the US Navy's newest dive-bomber, the Helldiver, which also proved rugged in service and carried a fairly large bomb load. When the Japanese committed both of their super battleships in the defense of the Philippines in October 1944, the power of American carrier aircraft proved sufficient to sink Musashi. Only months later, in April 1945, American aircraft repeated their performance against Yamato.