At 12:32 on 7 April 1945, a lookout on the bridge of the battleship Yamato spotted the first wave of American carrier aircraft. Less than two hours later the largest battleship ever built rolled over and blew up, sending a mushroom cloud thousands of metres into the sky, reportedly visible from Kagoshima on Kyushu.

Yamato never got anywhere near Okinawa, the island she had been sent to defend. She never came within sight of an American surface warship. She was sunk entirely by aircraft, launched from carriers she could not reach, flown by crews who could take their time because no Japanese fighters were overhead to stop them.

Operation Ten-Go was the last major sortie of the Imperial Japanese Navy. It is often told as a one-way suicide mission with fuel only for the outward trip. The truth is a little more complicated, and the way the US Navy took Yamato apart is a masterclass in how carrier aviation ended the age of the battleship.

Have we no more ships?

By the spring of 1945 the Combined Fleet was a shadow. Most of its surviving heavy ships sat in home ports, short of fuel and with almost no carrier aircraft or trained aircrew left. When American forces landed on Okinawa on 1 April, the Imperial Japanese Army planned massed kamikaze air attacks. The Emperor, briefed in March, reportedly asked what the Navy was going to do.

The answer, drafted under Admiral Soemu Toyoda, was Ten-Go. Yamato and nine escorts would fight their way to Okinawa, beach themselves between Higashi and Yomitan and fire as shore batteries until they were destroyed. The crews would then fight on land. Almost no air cover could be provided.

Vice Admiral Seiichi Itō, who would command the force, thought the plan futile and refused to order it. On 5 April Vice Admiral Ryūnosuke Kusaka flew to Tokuyama to persuade him and his captains; the argument that finally won them over was that the sortie would draw American aircraft away from the kamikaze attacks. About 80 new, sick or infirm crew members were sent ashore, including 67 naval cadets who had arrived days earlier.

The one-way fuel myth

The best-known detail of the story is that Yamato was given fuel for the outward voyage only. There is truth in it: the plan did call for the ships to take on just enough oil to reach Okinawa. What went into the tanks was another matter.

Local base commanders at Tokuyama issued far more than ordered. Yamato took on fuel amounting to about 60 per cent of her capacity, according to one detailed account of the ship. Takekuni Ikeda, a Yahagi survivor writing in the US Naval Institute's Naval History magazine in 2007, learned after the war that every ship sailed fully fuelled, and the US Navy's history command says they received as much fuel as was available.

Yarnhub's animated account of Yamato's final battle, one of the most-watched films on the operation.

Whether that would have been enough to steam home is still debated. The point is that Ten-Go was a suicide mission because of its orders, not because of its fuel gauges. The ships were meant to beach themselves at Okinawa, and no one planned a return voyage.

Watched all the way south

The Americans knew Ten-Go was coming before it sailed. Codebreakers had read the Japanese radio traffic, and conclusive intelligence arrived on 5 and 6 April. Yamato, Yahagi and the eight destroyers left Tokuyama on the afternoon of 6 April, and that evening the submarines Threadfin and Hackleback spotted them in the Bungo Channel, too fast to attack but easy to shadow.

The next morning PBM Mariner flying boats took over. Yamato fired her 46 cm main guns at them with special anti-aircraft shells, but could not shake them off. Admiral Raymond Spruance, commanding the Fifth Fleet, had ordered Rear Admiral Morton Deyo's older battleships to prepare a surface action. Mitscher, an aviator who had spent his career arguing that carriers could do what battleships could, wanted the kill for his aircraft.

Accounts of the command decision differ. In Navy lore Spruance simply signalled Mitscher: You take them. Other accounts have Mitscher launching his strike before he had told Spruance. Either way, from about 10:00 Task Groups 58.1 and 58.3 launched 280 aircraft, and Task Group 58.4 added more than a hundred. Not all of them found the target; USS Hancock's group, launched late, never located the Japanese force.

Port side, port side, port side

The attack was carefully choreographed. Hellcats and Corsairs went in first, strafing, firing rockets and dropping light bombs to distract the gunners. SB2C Helldivers dived almost vertically with heavy bombs. The Avengers made their low, dangerous torpedo runs while the gunners were busy, and they concentrated on Yamato's port side. Hitting one side again and again meant flooding one side, and a list that would eventually capsize her.

Yamato carried a huge anti-aircraft battery, but her gunners aimed visually, and American pilots judged that most of their fire was going wide. The first bombs hit at 12:41 and the first torpedo struck the port bow at 12:45. Yahagi was hit in her engine room at 12:46 and stopped dead. She took at least seven torpedoes and 12 bombs before she sank at 14:05.

The second and third waves concentrated on Yamato. Bombs wrecked her upper decks and cut power to the gun directors, so the anti-aircraft guns had to be aimed by hand. Torpedoes kept slamming into the port side. At 13:33, to stop the list from capsizing the ship, the damage-control team counter-flooded the starboard engine and boiler rooms. Several hundred men at their stations drowned without warning.

Drachinifel's detailed analysis of Operation Ten-Go, including the plan, the American strike and why Yamato could not survive it.

14:23

With her starboard engines gone and her rudder jammed, Yamato slowed to about 10 knots and could no longer steer. Shortly after 14:00 Itō cancelled the operation and ordered the surviving ships to rescue the crew. Her radios were wrecked, so the order went out by signal flags. Itō and Captain Kōsaku Aruga went down with the ship.

By 14:20 she had lost power and was rolling over to port. Three minutes later she capsized, and as she turned over a forward magazine exploded. The blast threw a mushroom cloud thousands of metres into the air. Of her crew of about 3,332, an estimated 3,055 were lost; the historian Samuel Eliot Morison counted 269 survivors. Across the whole force, between roughly 3,700 and 4,250 Japanese sailors died, depending on the source.

The destroyers Asashimo, Hamakaze, Isokaze and Kasumi were sunk or scuttled. Suzutsuki, her bow blown off, reached Sasebo by steaming in reverse. The Americans lost 10 aircraft and about a dozen airmen killed; some downed crews were rescued by seaplane or submarine. The same day, kamikazes hit the carrier USS Hancock, the battleship USS Maryland and the destroyer USS Bennett off Okinawa.

The end of the battleship age

Yamato's sister Musashi had already been sunk by carrier aircraft in the Sibuyan Sea in October 1944. Operation Ten-Go removed any lingering doubt. A battleship of nearly 72,000 tonnes with the largest guns ever mounted at sea, escorted by a cruiser and eight destroyers, was destroyed in about two hours by aircraft flying from carriers far beyond the reach of her guns.

Mitscher's argument had won. Deyo's battleships never fired a shot at her. In Japan, Yamato became a symbol of the end of the empire whose ancient poetic name she bore, a heroic, futile sacrifice in popular memory. For aviators the lesson was simpler: a fleet without air cover is a target.

World War 2 in Colour on the destruction of Yamato during Operation Ten-ichi-go, including American footage of the attack.

Sources: Wikipedia (Operation Ten-Go, Japanese battleship Yamato), US Naval History and Heritage Command (H-Gram 044), Takekuni Ikeda (Naval History, US Naval Institute, 2007), Robert Gandt (HistoryNet), Richard Sisk (Military.com), Samuel Eliot Morison, Garzke and Dulin