Henry VIII's flagship Mary Rose was sunk by a French cannonball and this was covered up by political spin, according to a new academic study.
Until now it was believed a combination of wind and tide pressed Mary Rose over, causing her gun ports to flood in a 16th Century battle in the Solent.
But University of Portsmouth geographer Dominic Fontana said the truth was withheld to maintain the Navy's image.
Mary Rose sank with the loss of more than 400 lives on 19 July 1545.
By claiming the ship was toppled by wind and an incompetent crew, the Navy's supremacy was maintained, Henry VIII's pride remained intact and the French were unable to claim victory, said Dr Fontana.
"The Mary Rose was holed by French gunfire received from an advance party of fast, oar-powered galleys which were heavily armed," he said.
"She would have quickly taken quite a quantity of water into her hull before she manoeuvred to bring a broadside of guns to bear on the attacking French galleys."
That fateful manoeuvre was her undoing he said because the sudden movement of water in the hold caused her to capsize.
Mary Rose sits in an atmospherically controlled museum in Portsmouth
Dr Fontana, a former photographer who worked on the Mary Rose project, used Geographical Information Systems (GIS) technology to create a map from the Tudor Cowdray Engraving of the battle in the Solent.
"The Mary Rose dropped into exactly the correct place where she sank," he said.
"It showed that the Cowdray Engraving gave a really good geographical impression of what went on."
He then integrated this data with tidal currents hour by hour over the period of the battle.
Dr Fontana said: "Mary Rose was hit by French gunfire and despite valiant efforts being made by her crew she capsized just one mile from Southsea Castle from where King Henry VIII was watching.
"Those onshore would not have known anything about flooding in the hull caused by a French hit on the ship and it would have appeared as though she had been caught by a freak gust of wind and blown over."
Mary Rose sank after 34 years of service, fighting in two wars against the French and one against the Spanish.
Millions of people watched the salvage operation on television in 1982.
String of theories
A spokeswoman for The Mary Rose Trust, the charity that preserves the ship, said the new research was the latest in a string of theories on the fate of the warship.
Dr Fontana added that tools and skeletal remains found in the hold show men, who would otherwise not have been there in the middle of a battle, were working in the dark to plug the hole made by the cannonball.
Christopher Dobbs, archaeologist at the Mary Rose Museum, said: "As archaeologists, we have studied the remaining evidence from the ship.
"But, as we have nothing left of the port side, it is helpful for people from other fields to contribute their own theories and ideas."
Dr Fontana's research will be featured in What Really Sank The Mary Rose on The History Channel on 24 November.