COEFFETEAU, NICOLAS (1574-1623), French theologian, poet and historian, was born at Saint-Calais. He entered the Dominican order and lectured on philosophy at Paris, being also "ordinary preacher" to Henry IV., and afterwards ambassador at Rome. In 1606 he was vicar-general of the congregation of France, and received from Marie de' Medici the revenues of the sees of Lombez and Saintes. He also administered the diocese of Metz, and was nominated to that of Marseilles in 1621, but ill-health obliged him here to take a coadjutor. Coeffeteau won considerable distinction in the controversy against the Protestant reformers and also wrote a _History of Rome from Augustus to Constantine_. Many of his theological writings were collected in one volume (Paris, 1622), and at the time of his death in 1623 he was engaged on a translation of the New Testament which is still in manuscript.
COEHOORN, MENNO, BARON VAN (1641-1704), Dutch soldier and military engineer, of Swedish extraction, was born at Leeuwarden in Friesland. He received an excellent military and general education, and at the age of sixteen became a captain in the Dutch army. He took part in the defence of Maastricht in 1673 and in the siege of Grave in the same year, where the small mortars (called coehorns) invented by him caused the French garrison considerable trouble (Seydel, _Nachrichten über Festungskriege_, Leipzig, 1818). He was made a colonel for his gallant conduct at the battle of Seneff (1674), and was present also at the battles of Cassel (1677) and Saint Denis (1678).
The circumstances of the time and the country turned Coehoorn's attention to the art of fortification, and the events of the late war showed him that existing methods could no longer be relied upon. His first published work, _Versterckinge de Vijfhoeks met alle syne Buytenwerken_ (Leeuwarden, 1682), at once aroused attention, and involved the author in a lively controversy with a rival engineer, Louys Paan (Leeuwarden, 1682, 1683; copies are in the library of the Dutch ministry of war). The military authorities were much interested in this, and entrusted Coehoorn with the reconstruction of several fortresses in the Netherlands. This task he continued throughout his career; and his experience in the work made him the worthy rival of his great contemporary Vauban. He formulated his ideas a little later in his chief work, _Nieuwe Vestingbouw op en natte of lage horizont_, &c. (Leeuwarden, 1685), in which he laid down three "systems," the characteristic feature of which was the multiplicity and great saliency of the works, which were calculated and in principle are still eminently suited for flat and almost marshy sites such as those of the Low Countries. He borrowed many of the details from the works of his Dutch predecessor Freytag, of Albrecht Dürer, and of the German engineer Speckle, and in general he aimed rather at the adaptation of his principles to the requirements of individual sites than at producing a geometrically and theoretically perfect fortress; and throughout his career he never hesitated to depart from his own rules in dealing with exceptional cases, such as that of Groningen. Subsequent editions of _Nieuwe Vestingbouw_ appeared in Dutch (1702, and frequently afterwards), English (London, 1705), French (Wesel, 1705), and German (Düsseldorf, 1709).