Object Title

4.4 in mortar - Coehorn mortar

4.4 in mortar - Coehorn mortar



Object Number



Old Tower Collection.

Physical Description

The reinforce bears in relief the entwined monogram of George III, the breech being incised I.P. VERBRUGGEN FECERUNT. Ao. 1779 No: 1. 14. Below the vent is the weight 0-3-2, and the number 114 is repeated on the under side of the breech


Dimensions: Length: 1 ft 1 in (13 in) (33 cm), Diameter chamber: 2.20 in (5.6 cm) Weight: 3 qtrs 2 lb (39 kg)


Serial Number 114


4.4 in (11.2 cm)

Inscriptions and Marks

Left trunnion: E3 46


Places England

Bibliographic References

H.L.Blackmore, The Armouries of the Tower of London, Ordnance Catalogue, H.M.S.O. London 1976, P.100.


'John Verbruggen'
Born in Enkhuizen, Holland, in 1712, became Master Founder of the Dutch Admiralty Bell and Cannon Foundry there in 1746. In 1755 he was appointed Master Founder at The Hague ordnance factory using the new technique of solid casting and barrel boring. Here he was joined by his son Peter (b.1734). He incurred the enmity of General de Creuznach, the inspector General of Artillery, and from 1762 his methods of gunfounding were the subjects of numerous enquiries and criticisms. In 1765 his foundry ceased production and he was eventually replaced by Jean, the son of the famous Swiss gunfounder Samuel Maritz. In spite of this blow to their reputations John and Peter Verbruggen were chosen by the British Board of Ordnance to succeed Andrew Schalch as joint Master Founders at Woolwich in 1770. Here they introduced a new type of horizontal boring machine, models of which can be seen in the Rotunda Museum, Woolwich, and the Science Museum, London. John died in 1782, Peter continuing alone until his death in 1786. A collection of fifty watercolour drawings of c.1776 showing the various processes of cannon founding at the Royal Brass Foundry under the Verbruggen's direction, now in a Dutch private collection, may have been painted by either John or Peter. Both men had artistic talent, John, the more accomplished, exhibiting in England in 1772. See M. H. Jackson & C. de Beer, 'Eighteenth Century Gunfounding' (Newton Abbot, 1973). Cf. Nos. 60, 106-7.

In 1713 the first 'Cohorn' mortars appear and in 1726 Royal mortars are listed as well. The Cohorn mortar was the smallest of the standard mortars and was named after its inventor the Dutch military engineer Baron Menno van Cohorn (or Coehorn), 1641-1704. Known as the Dutch Vauban he was renowned mainly for his methods of siegecraft and fortification. His mortars were first used at the siege of Grave in 1674.