Eight 13th Century catapult shots have been discovered “perfectly preserved” outside the walls of a castle in Warwickshire.

English Heritage said the shots would have been fired during the siege of Kenilworth Castle in 1266, one of the longest sieges in English history when the country was in the grip of civil war.

The shots range between 1kg and 105kg in weight, with some being found just below the surface of the ground.

English Heritage said the discovery was made during a project to improve accessibility around Kenilworth Castle.

Will Wyeth, English Heritage’s properties historian, said: “We were able to immediately link these findings to the 1266 siege because of similar finds recovered in the 1960s.

“However, it’s not every day we get lucky enough to stumble across historical remains like this by chance.”

For a total of 172 days between 25 June and 13 December 1266, Kenilworth Castle was under constant attack in one of the most significant military contests of Henry III’s reign.

The king’s conflict with his nobles had escalated into civil war some years prior.

After almost six months, the resistance efforts of the rebels fell to starvation and disease, and surrendered Kenilworth Castle to Henry, who then gave it to his son, Edmund, Earl of Lancaster.

Mr Wyeth said: “Imagine the surprise of the team when we unearthed these impressive stone projectiles that are nearly 800 years old.

“These would have caused some serious damage when fired from war machines.

“In fact, records show that one of Henry III’s wooden siege towers, containing around 200 crossbowmen, was destroyed by just one well-aimed missile.”

King Henry III used a large arsenal of weaponry in his attacks on Kenilworth Castle, including 60,000 crossbow bolts and nine siege engines, including catapults, to attempt to breach the 14-foot thick walls.

However, the garrison inside had also equipped themselves with similar siege engines.

It is the stone projectiles that were being fired from both sides that have been found outside the West castle walls.