Archaeologists announced today that they have located not just the site of the Battle of Bosworth, but the spot where – on 22 August 1485 – Richard III became the last English king to die in battle when he was cut down by Tudor swords.

Nearby Henry Tudor was crowned Henry VII, with the crown which had tumbled from the dying Richard's head.

The crucial evidence, including badges of the supporters of both kings, sword mounts, coins and 28 cannonballs, was found in fields straddling Fen Lane in the Leicestershire parish of Upton, where no historian had looked before.

The haul adds up to more than the total found on all other medieval battle sites in Europe.

"It took us five years to locate it, but there it is, there is the battle of Bosworth," said Glenn Foard, the internationally renowned expert who led the hunt, looking over the landscape of low snow-­covered hills, where on a hot summer day more than 500 years ago the course of English history changed.

The site was located by archaeologists using metal detectors across hundreds of acres, and poring over the evidence of medieval place names to match them to accounts of the battle. Their finds suggest a sprawling fight, with the two armies facing one another in straggling lines almost a kilometre in length.

Frank Baldwin, the chair of the Battlefields Trust charity, said: "This is a discovery as important to us as Schliemann discovering Troy." The military historian Professor Richard Holmes, who two years ago rode Henry's route from Wales to the battlefield in full Tudor costume, said: "This is certainly the most important discovery about Bosworth in my lifetime."

Farmer Alf Oliver was astonished at the discovery in his fields straddling Fen Lane, outside all the parishes which have vied for centuries to claim the honour and three kilometres south-west of the visitor centre on Albion Hill. Fen Lane was once a Roman road linking Leicester and Atherstone, the towns from which Richard and Henry approached the battle.

One of the crucial finds, the largest of the cannonballs nicknamed "the holy grapefruit" by the archaeologists, was found just behind one of Oliver's barns. Another key discovery was a silver boar no bigger than a thumbnail, battered but still snarling in rage after 500 years. It was found on the edge of a field still called Fen Hole, which in medieval times was a marsh that played a crucial role in the battle, protecting the flank of Henry Tudor's much smaller army. The marsh was drained centuries ago, but Oliver said it still gets boggy in very wet summers.

After a charge in which Richard came within almost a sword's reach of Henry, he lost his horse in the marsh, a moment immortalised in the despairing cry Shakespeare bestowed upon him: "A horse! A horse! My kingdom for a horse!"

"The fact that this little boar is Richard's personal emblem, and made in silver gilt, means that it can only have been given to one of the closest members of his retinue. The man who wore this would have fought and died at Richard's side," Foard said.

"If you were to ask me what was the one find I would dream of making, which would really nail the site, it would be Richard's boar emblem on the edge of a marsh."

Other finds include a gold ring twisted like a pretzel, and an inch of gilded sword mount from a weapon of such high status that it can only have belonged to one of the aristocrats who led the battle forces.

The search was launched as part of a Heritage Lottery funded revamp of the visitor centre, which is left with the consolation that it may well have been part of Richard's camp on the eve of the battle, and part of the rout as his troops were forced into desperate retreat by Henry's triumphant men.

Foard believes a more likely site now for the battlefield coronation is Crown Hill, a hillock near the newly identified site, which was renamed soon after the battle.

Local historian John Austin brought the team a further gift: he owns the domain title battleofbosworth.com, and today he presented it to them to mark the ­occasion.