Coehoorn, or COHORN, MENNO, BARON VAN, called the Dutch Vauban, was the son of a captain of infantry, and born near Leeuwarden in 1641. He studied fortification and mathematics at Franeker, and already captain of a company in his sixteenth year, he greatly distinguished himself at the siege of Maestricht, and in various battles. At the siege of Grave, in 1673, he demonstrated that the small portable mortars named after him might be advantageously employed. Coehoorn covered himself with honour at Senef (1674), before Kaiserswerth (1689), and at Fleurus (1690). He fortified Namur, and defended it against Vauban in 1692; besieged that fortress in 1695, and retook it; was appointed lieutenant-general and director-in-chief of the Dutch fortifications, and fortified several towns, of which Bergen-op-Zoom was considered his masterpiece. In the war of the Spanish succession he defeated the French more than once, and took Huy and Limburg. He died at the Hague, on his way to meet Marlborough, March 17, 1704. He left two important works on fortification.
Coehorns—named from the military engineer who introduced them—are small bronze Mortars (q.v.), cwt. in weight, and of inches calibre. Being easily carried, they are useful in sieges, to annoy working parties, and in situations where guns cannot be employed, such as the attack of hill-forts in India.