BBC historian Professor Michael Wood believe he has discovered the real location of the Battle of Brunanburh, one of the most decisive battles in British medieval history - a lay-by off the A1 near Burghwallis.
The bloody scrap saw a West Saxon army go head to head against a combined hoard of Vikings, Scots and Irish in 937 - and Professor Wood thinks the battle took place at the site of Robin's Hood Well.
Despite the battle's significance, mystery has surrounded its true location for over 1,000 years, with more than 30 locations proposed across England.
A consensus emerged that the battle took place in Bromborough on the Wirral, Merseyside, but Prof Wood is convinced it actually unfolded 100 miles away in South Yorkshire.
Prof Wood said a battle site on the main route from York down into England's Danish heartland in Mercia is a far more likely location for the battle.
He said: "The evidence clearly points to the Battle of Brunanburh taking place in the region south of York which was the centre of conflict between the Northumbrians and the West Saxon kings during the second quarter of the 10th century."
He says Bromborough is not mentioned in the 1086 Domesday Book and doesn't appear until the 12th century.
There are also doubts about whether Brunanburh should be spelt with a single or double 'n', as it was by several 10th and 11th century chroniclers.
Altering the spelling to a double 'n' and Brunnanburh changes the Old English meaning from 'Bruna's fort' to 'the fort at the spring', which could refer to Robin Hood's Well.
Prof Wood said this could be interpreted as 'the dun by the Went' or 'Went Hill' in south Yorkshire, near to Robin Hood's Well.
The battle is seen as a key date in British history.
Had King Athelstan - grandson of Alfred the Great - been defeated it would have been the end of Anglo-Saxon England.
But upon victory, Britain was created for the first time and Athelstan became the de facto King of all Britain, the first in history.
The Robin's Hood Well monument was originally on the route of the A1 but was moved a few hundred yards south in the 1960s when the road was expanded into a dual carriageway.
The Grade II listed monument dates from 1710 and was designed by Sir John Vanbrugh for the Earl of Carlisle.