Marine archaeologists say they have found the deepest-ever shipwreck, which they believe to be a famed Second World War destroyer that fought in the Battle of Leyte Gulf.

Explorers aboard the RV Petrel encountered the shattered remains of an American Fletcher-class destroyer 6,220m beneath the Philippine Sea, where one of the pivotal naval battles of the war took place in October 1944. According to the Guinness World Records website, the previous deepest wreck was a German vessel found at 5,762m.

Video footage shows mangled gun emplacements, two funnels and other, unrecognisable hunks of twisted metal strewn across the seabed. “There is no hull structure intact that we can find. This wreck is completely decimated, it is just debris,” the crew of the Petrel said in a video released on Wednesday.

The experts said they believed they had uncovered the resting place of the USS Johnston, a member of the famous “Taffy 3” unit which steamed into battle against the Imperial Japanese Navy’s (IJN) most powerful battleship in order to protect US troops fighting on the beaches at Leyte.

“This wreck is either the Johnston or the Hoel,” the Petrel team said. “This wreck is in the southern part of where the battle took place and this is one of the reasons why we believe this is the Johnston, because she sank later, after Hoel did.”

Wreck of Leyte Gulf warship discovered Show all 5 1 /5 Wreck of Leyte Gulf warship discovered Wreck of Leyte Gulf warship discovered USS Johnston wreckage Twisted debris from the sunken destroyer RV Petrel Wreck of Leyte Gulf warship discovered USS Johnston Pictured in 1943 in Washington state US Navy Wreck of Leyte Gulf warship discovered USS Johnston wreckage A gun emplacement RV Petrel Wreck of Leyte Gulf warship discovered USS Johnston wreckage RV Petrel Wreck of Leyte Gulf warship discovered USS St Lo explodes The escort carrier USS St Lo explodes following a Japanese kamikaze attack US Navy

The landings at Leyte were the first clash in the US-led campaign to retake the Philippines, which Japan’s military had overrun two years earlier.

Johnston, a comparatively lightly armed and armoured ship, was part of a detachment left unguarded off Samar Island by larger American vessels thanks to Japanese misdirection. The admiral in charge of Taffy 3’s protector force had chased after a decoy group of Japanese aircraft carriers, taking with him warships which otherwise might have gone toe-to-toe with the approaching enemy.

A marauding IJN group of battleships, cruisers and destroyers caught Taffy 3 by surprise near the San Bernardino Strait on 25 October. Johnston, along with similar light ships, turned her torpedos and diminutive 5in guns on the much larger enemy vessels, while the small “escort” aircraft carriers they were protecting launched a string of air attacks to help.

Among the enemy flotilla was the Yamato, the largest battleship ever built, bristling with a main battery of nine 18in guns. “We felt like little David without a slingshot,” Johnston’s gunnery officer later reported, according to a US Navy history of the battle.

After spotting the Japanese marauders, the destroyer’s skipper took the initiative by steaming straight toward the enemy battle line, pouring shells and torpedoes into the heavy cruiser Kumano and sustaining heavy-calibre hits in the process.

The US Navy’s account added: “Despite the grave damage, no torpedoes remaining, and reduced speed and firepower, Johnston commenced a second attack [by] firing 30 rounds into a 30,000-ton Japanese battleship.

“One by one, Johnston took on Japanese destroyers, although [she] had no torpedoes and limited firepower. After two and a half hours, Johnston, dead in the water, was surrounded by enemy ships. At 9.45am, Evans gave the order to abandon ship. Twenty-five minutes later, the destroyer rolled over and began to sink.”

These and other heroics earned Taffy 3 a presidential unit citation and Johnston's skipper, Ernest Evans, a posthumous congressional medal of honour. The action prevented Japanese ships from attacking the soldiers fighting to retake Leyte.

The wider battle in Leyte Gulf, which took place over several days, effectively ended the usefulness of the Japanese surface fleet. It is also notable as the battle in which the Japanese debuted organised kamikaze attacks – a tactic which claimed the escort carrier USS St Lo during the battle off Samar.

The Petrel expedition was founded by the late Microsoft co-founder Paul Allen. Its team works with officials around the globe to find and document sunken ships.