Chilling hanging scenes and sailing ship scrawled by troops amid threat of French invasion are found on 1790s door at Dover Castle

• Door dates back to the 1790s and was found in Dover Castle's St John's Tower
• Soldiers were stationed there amid the threat of invasion by Napoleon's troops 

Macabre depictions of hangings and a detailed carving of a sailing ship feature in soldiers' graffiti on a newly-discovered 18th century door from Dover Castle.

The door, which dates back to the 1790s, has been conserved by experts after being found in the castle's St John's Tower.

Soldiers stationed at the fort in Kent amid the threat of invasion by Napoleon's forces from France carved around 50 pieces of graffiti on the door.

As well as the gruesome hanging scenes, dates including 1789 - the year of the French Revolution - are also inscribed.

Also present is a detailed and accurate carving of a single-masted sailing ship, most likely an eight-gun cutter - a fast vessel that was used by the Royal Navy, the government's Revenue Service and smugglers and privateers.

The door was originally housed on an upper floor in Dover Castle's St John's Tower. 

It is now going on display as part of new exhibition Dover Castle Under Siege, during which the castle's northern defences, including Georgian underground tunnels, will be opened up. 

The castle underwent a major transformation in the 1970s when the threat of French invasion loomed.

Because it housed thousands of soldiers, it was necessary to build new barracks and create new positions to defend from cannon fire.

St John's Tower would have been guarded by between six and 12 men.

With hours spent doing very little, the men on duty put their questionable artistic talents to good use with knives and possibly bayonets. 

The other dates on the door are 1798 - during the period of reconstruction - and 1855, when changes were planned to St John's Tower.

There are at least nine depictions of hangings, including one example where a condemned man wears a uniform and bicorne hat.

Another curious symbol depicting a glass or chalice, surmounted by an elaborate cross, may be a representation of Christian holy communion.

After its discovery, the door was removed from St John's Tower to protect and preserve it for future generations. 

Experts also carefully removed paint layers from the decorative surface on the door and then the wood was cleaned, toned and treated. 

Paul Pattison, English Heritage's senior properties historian, said: 'Scaling a ladder to the upper floor of St John's Tower and seeing these remarkable carvings on the door was an astonishing discovery for us. 

'This graffiti gives a unique glimpse into the minds of these soldiers, especially during such a charged period of time. 

'As a result of the impending threat of war from across the Channel, Dover was a hive of activity with ships filling the harbour and coloured military uniforms a constant presence in the castle and town. 

'What makes this door such an extraordinary object is that it is a rare and precious example of the ordinary person making their mark; whether that be simply for the purpose of killing time or wanting to be remembered.'

St John Tower's Door will go on display at Dover Castle in July as part of Dover Under Siege.