MENNO, BARON DE** (1641–1704), the rival and contemporary of Vauban, was born at Leeuwarden, in Friesland. He inherited a taste for military science from his father; and having studied mathematics at Franeker, under his uncle Fullenius, he entered the service as captain when only sixteen. Having distinguished himself at the siege of Maestricht, and afterwards at the battles of Senet, Cassel, St Denis, and Fleurus, he was promoted to the rank of colonel. In the campaign of 1675, he performed an important service at the siege of Grave, by successfully employing the means which he had invented for crossing the fosses of fortified places, and thus carrying a bastion without a counterscarp, the access to which was defended only by the river Meuse; a service for which he received, on the spot, the warmest commendations of Vauban. At a subsequent period Cohorn applied his theory of fortification to the fortress of Coverden; and during the war between Holland and France distinguished himself by new exploits. At the siege of Namur he defended Fort William against Vauban in the most gallant and determined manner; but was at last compelled to yield to superior force, and surrender the work to his great rival. In 1695, however, he recovered the fort, when defended by Boufflers. This alternate taking and retaking of Namur, under Vauban and Cohorn, is considered as illustrative of their respective systems; Vauban sparing his artillery and men, and trusting principally to the efficiency of his works; whilst Cohorn, sacrificing everything to the desire of abridging the siege, by striking the besieged with surprise and terror, was equally prodigal of means and of men. In 1702, Cohorn, now appointed lieutenant-general, published his *New Method of Fortifying Places*; and in the following year he applied his system to the conduct of the siege of Bona, which he forced to capitulate in three days. He died, March 17, 1704, at the Hague, whither he had gone, at the invitation of Marlborough, to concert measures for the ensuing campaign. Bergen-op-Zoom, which was fortified by Cohorn, is generally considered his masterpiece. It was, however, taken by the French under Löwendahl in 1747, after a feeble defence; and in 1814 an attempt to carry it by a coup-de-main, planned by Lord Lynedoch, miscarried only by an extraordinary accumulation of adverse accidents. See **Fortification.**

**COHORT,** in Roman Antiquity. See **Army,** vol. iii., p. 631.