Koehler Depressing Carriage

It was devised to enable cannon to be fired at a steeply downward-facing angle and was made necessary by the peculiar circumstances that the British Army faced during the Great Siege of Gibraltar between 1779 and 1783.

The carriage saw active service during the siege, when it was used to support the British counter-bombardment of Spanish and French artillery batteries during the successful defence of Gibraltar.

The British controlled the high ground of the Rock of Gibraltar, which reaches a height of 411.5 metres (1,350 ft) at its north end.

Although this was a major advantage for the British gunners, as it gave them an increased range and a clear view of the enemy, it also posed significant problems.

It consequently exposed them to severe danger as they had to load the guns in full view of enemy counter-fire, rather than out of sight in an embrasure or battery.

[1] The carriage was first put into operational use in the afternoon of 15 April 1782, when Koehler demonstrated it to the Governor of Gibraltar, General George Augustus Eliott, and other officers of the garrison.

This was resolved by an 1870s update to the design which saw the addition of a large wheel at the back, connected to a screw mechanism, which enabled fine tuning of the angle.