At the outbreak of World War II the Imperial Japanese Navy had the four upgraded battle cruisers that were 25 or 40 years old, the seven obsolete WWI era veterans and the following:
- Yamato – nine 18.1 inch guns (the largest ever mounted on a warship); commissioned in December 1941. While sailing to Leyte Gulf the Yamato’s task force was attacked in the Palawan Passage on October 23, 1944 by US submarines Darter and Dace. They sank two accompanying heavy cruisers, Atago and Maya. At the battle of the Sibuyan Sea planes from the US carriers Intrepid (CV-11) and Cabot (CVL-28) damaged Yamato with two 500 pound bombs. Yamato helped sink USS Gambier Bay (CVE-73) on October at the battle off Samar. It is not known what other ships Yamato fired at or damaged. On April 7 1945 Yamato was sunk by US warplanes about 180 miles southwest of Kyushu while sailing to Okinawa.
- Musashi – nine 18.1 inch guns and was commissioned in August of 1942. She saw no action until March 29, 1944 when she departed Palau under cover of darkness and was torpedoed (1 hit out of 6 launched) by US submarine Tunny. Musashi endured terrible bomb and torpedo damage from American carrier aircraft before sinking about 20 miles north of Sibuyan Island on October 24, 1944. Musashi‘s wreckage was found in March 2015 by the team led by Paul Allen (co-founder of Microsoft).
- Shinano was originally intended to be the third Yamato class battleship. However, the Imperial Japanese Navy reconsidered, and had her built as a support aircraft carrier which would have 47 of her own aircraft. Shinano would carry up 120 replacement aircraft for other carriers, and would haul extra fuel, ammunition and food. Roughly south of Kyoto and Osaka Shinano was sunk by US submarine Archerfish on November 29, 1944 ten days after Shinano was hurriedly commissioned. As completed, Shinano had a length of 266 meters (872 ft) , a beam of 36 meters (119 ft) and a draft of 10.3 meters (33 ft 10 in). She displaced 65,800 metric tons at standard load, 69,151 metric tons at normal load and 73,000 metric tons at full load. Shinano was the largest aircraft carrier yet built for ten years and remains the largest warship ever sunk by a submarine.
- Mutsu – eight 16 inch guns; commissioned 1921; modernized 1934-6. Mutsu saw nocombat action and on June 8 1943 was moored in the Hashirajima fleet anchorage, with 153 personnel from the Tsuchiura Naval Air Group aboard for familiarization. At 12:13 the magazine of #3 turret exploded ripping the ship in two and killing 1,121 men including all but 13 visiting airmen. Two turrets and their guns were salvaged during the 1970s from the wreck and are currently on display in Japan at the Imperial Japanese Naval Academy at Etajima, at the Kure Maritime Museum, and at the Museum of Maritime Science at Odaiba. Her recovered chrysanthemum crest is at the Yasukuni Museum and Shrine. There is also the Mutsu Memorial Museum in Towa in Yamaguchi Prefecture.
- Nagato – eight 16 inch guns; commissioned 1920; modernized 1934-6. Nagato saw no combat action until she was strafed at the battle of the Philippine Sea June 19–20, 1944. On October 24 1944 Nagato was attacked by multiple waves of US carrier aircraft and was hit by two bombs. She fired at American escort carriers during the battle off Samar the next day, but scored no hits. She was struck in the bow by two bombs on October 25, but survived to become a moored gun platform. She was eventually sunk during atomic bomb testing in 1946.