The Coehorn mortar is named after its Dutch designer Baron Menno van Coehorn (1641-1704). The British model was cast in brass and was slightly longer and with a larger calibre then the Dutch model. Over the century and half of its existence several changes were made to the weight, calibre and dimensions.

The model on display at the Army Museum was designed by Gother Kerr Mann, who was later to become Chief Engineer for the construction of Fitzroy Dry Dock on Cockatoo Island. Mann became aware of the difficulties experienced by the British troops in the Maori War and in 1846 arranged, at his expense, for the construction of Coehorn mortars, at the foundry of Peter Nicol Russell in Sydney.

On 4 October 1846 Lieutenant Colonel CB Despard, commander of the British Force in New Zealand, reported the arrival of the Headquarters of the 58th Regiment in New Zealand with four mortars ‘…which had been cast in Sydney…’. On 4 November he reported the arrival of a detachment of the 99th Regiment with military stores and ‘…three more mortars…’. ¹

An old chief of the Ngapuhi tribe commented on the mortars:
‘These guns, however, never killed anyone. They are a very vexatious invention for making people deaf and preventing them from getting any sleep.’ ²

When hostilities ceased the mortars were placed in storage and during the Maori wars of 1860 to 1864 were again in use.

¹ Army Museum of New South Wales, Historic Information Leaflet. Equipment Series No 1. Coehorn Mortar.

² Ibib.