Microsoft co-founder says his exploration vessel M/Y Octopus found the battleship off the coast of the Philippines

Sunk without trace in what some historians consider the greatest naval battle ever fought, the mightiest battleship ever built has been found off the Philippines by one of the world’s wealthiest men.

Paul Allen, the multibillionaire Microsoft co-founder, on Tuesday posted photographs of the wreck of the Musashi, a second world war Japanese battleship that, with its sister-ship the Yamato, was the largest and most heavily-armed warship ever launched.

“WW2 Battleship Musashi sank 1944 is FOUND,” Allen announced on Twitter, beneath a ghostly underwater photograph of the mammoth vessel’s rusting, coral-encrusted bow clearly bearing the chrysanthemum crest of the Japanese imperial family.

Other pictures taken on the floor of the Sibuyan Sea by a team from the Octopus, Allen’s luxury yacht and undersea exploration vessel, showed one of the warship’s enormous anchors and a heavily encrusted valve captioned: “RIP crew of Musashi, approximately 1,023 lost.”

Image taken by Paul Allen showing what Allen’s team believes is a valve wheel on the ship. Photograph: AP

Allen, who has devoted a small part of his estimated $17.5bn fortune to deep-sea and space exploration, said on his website that the discovery of the wreck, at a depth of more than half a mile, marked “an important milestone in the annals of World War II naval history”.

Designed to take on multiple enemy ships simultaneously, the Musashi was the second of the imperial Japanese navy’s colossal Yamato-class heavy battleships. Launched in November 1940, it measured 263m (863 feet) overall, weighed 73,000 tonnes fully laden, carried a crew of 2,500, and could travel at speeds of up to 27 knots (50 kph).

But what most alarmed the Allies was the warship’s terrifying armament, which included the largest-calibre guns ever fitted to a warship: nine 46cm (18.1in) cannon mounted in three triple turrets, each capable of firing up to two 1,460kg (3,220lb) armour-piercing shells a minute over a maximum range of 26 miles.

She was an awe-inpiring sight. “I had never,” the World War II Database records gunner Russ Dustan of the American aircraft carrier USS Franklin as saying, “seen anything as big in my entire life … It was huge.”

But mighty as she was, the Musashi was not invulnerable – especially to aerial attack. On October 18 1944, Japanese vice admiral Takeo Kurita sailed with a 67-strong fleet, including both the Musashi and Yamato, into the Sibuyan Sea, west of the Philippine island of Leyte, aiming to throw back an American landing and attack vulnerable US transport ships on the other side of the island.

At 8.10am on October 24 a spotter aircraft from the US carrier Intrepid spied the Japanese fleet, and by 10.27am, according to Japanese naval records, battle was formally engaged, with the Musashi’s massive guns in action for the first time.

But with few Japanese aircraft to fend off the airborne attacks, the enormous vessel eventually became a sitting duck, reduced to firing its mammoth guns into the water to send up huge spouts of water aimed at knocking the attacking aircraft out of the air.

“Running into one of these geysers was like running into a mountain,” one US pilot, Jack Lawton, was recorded as saying after the battle. “I felt the muzzle blast each time they fired. I could swear the wings were ready to fold every time these huge shockwaves hit us.”

Facebook Twitter Pinterest The Japanese battleship Musashi in October 1944. Photograph: Jiji Press/AFP/Getty Images

The last American attack was over by 3.30pm, according to the US Naval Historical Centre, leaving the Musashi listing heavily from some 37 direct torpedo and bomb hits (the figure is disputed). At 7.15pm, Captain Toshihira Inoguchi retired to his cabin, intending to go down with his ship. The order to abandon ship came 15 minutes later and at 7.36pm the Musashi capsized and sank. Of the crew of 2,399, only 1,376 survived.

Pitting combined American and Australian forces against the Japanese navy, the Battle of Leyte Gulf is widely considered to be the largest naval battle of World War II and is thought by some naval historians to be the largest in history.

Despite numerous witness accounts of the sinking, the exact location of the Musashi’s wreck was never clearly established. Allen, who co-founded Microsoft with Bill Gates in 1975 and is ranked by Forbes magazine as the 51st richest person in the world, said he began searching for the battleship more than eight years ago.

In a statement, the billionaire said his team conducted a bathymetric survey of the ocean floor to eliminate large areas from the search, then conducted the final phase of the search using a autonomous underwater robot, or AUV, to detect the wreckage on Monday. An ROV, or remote operated vehicle, fitted with a high-definition camera and operated from the Octopus, later successfully filmed the battleship.

Allen said he had long been fascinated by second world war history and was “honoured to play a part in finding this key vessel in naval history and honouring the memory of the incredible bravery of the men who served aboard her”.

The entrepreneur is also working on a project to put “cost-effective” cargo and manned missions into space, and launched SpaceShipOne, the first privately built craft to enter suborbital space, in 2004.