Downward Firing Gun from Gibraltar Siege 1782

During the Great Siege of Gibraltar by the Spanish and French from 1779 to 1783,in the War of American independence, the British defenders dug a gallery through the limestone high in the northern cliff of the Rock of Gibraltar, in order to bring fire down onto the Franco-Spanish siege lines on the isthmus separating the Rock from Spain.

This was tunnelled with great devotion by the forerunners of the Royal Engineers. However once the embrasures were made the key innovation was the downward firing cannons devised by one Lt Koehler. These used two revolutionary innovations. First the cannon barrel - not the whole cannon - recoiled upwards, rather as all modern artillery does now. Second the cannon barrel rotated 90 degrees on its base thus allowing the gunners to reload without exposing themselves on the cliff.

One also imagines that a third innovation was packing the cannon ball in tightly with wadding after it was inserted down the barrel onto the charge - so that it did not simply roll out before firing.

These cannons, when first fired reported great accuracy in hitting the besiegers works edging towards the base of the Rock.

The British and Hanoverians with great bravery held out against assaults and bombardments from land and sea and were in the end victorious, thus preserving Gibraltar as a British base and fortress.

Today Lt Koehler's gun - pictured here - looks down on Gibraltar airfield still used by the RAF, and also holiday jets.