Three amputated legs and evidence of a previously unknown firefight between French cavalry and the troops led by the Duke of Wellington have been found at the site of the Battle of Waterloo by British veterans.

Finding human remains at the battlefield is extremely rare as many of the mass graves were plundered and bones ground to be used as fertiliser in the years after the 1815 battle in Belgium.

25 veterans and serving soldiers, some of whom suffer from post-traumatic stress disorder, were taking part in the first dig at the Mont St-Jean farm buildings with British and Dutch archeologists.

Mont St-Jean served as the Duke of Wellington’s field hospital and was about 0.3 miles behind the Allied front line facing Napoleon’s French army.

The dig found 58 French and English musket balls on Monday in a concentrated area, which suggested French cavalry had swept into the grounds of Mont St Jean before a shootout with allied defenders. The dig was expanded after the surprise find.