A metal detectorist unearthed the fragments of the guns, thought to date back to the 15th Century, at the site in Towton, near Tadcaster.
The find contradicts the idea that guns were only used in that period of history to attack castles.
Experts say it sheds light on the use of guns by troops in medieval battles.
Tim Sutherland, an archaeologist visiting the University of York, said the unearthing of the parts of gun barrels was “incredibly important” – but possibly unlucky for the soldier who had been holding the weapon in the conflict in 1461.
The manufacturing of firearms in that period of time was notoriously unreliable, Mr Sutherland said.
He revealed the reason the guns were probably not found intact was that it was not uncommon for the weapon to explode in the user’s hands because of metal casting faults.