CORMONTAINGNE, LOUIS DE, bora about 1606, was a French engineer, who distinguished himself both by the services which lie performed in the field and by the improvements which he made in the art of fortification. lie was present as an engineer at the sieges of Landau and Fribourg In 1713; and three years afterward, he addressed a Memoir on Fortification to M. le Pelletier de Souzi, who at that time held the rank of Intendant Gdndral des Fortifications de France. In 1734 he was appointed by the Comte, afterwards the llardchal Due de Bollisle, to direct the siege of Traerbach; and when the division which performed that service rejoined the main army he accompanied it; the siege of Philisbourg being then undertaken Cormontaingne was employed to superintend the operations; and it is sold that his successful attacks on two of the works were the imme diate Muse that the place was surrendered.
In the year 1714 ho conducted, in Flanders, the sieges of Tlenin, Ypres, La Knoque, and Fumes; and, in Germany, that of Fribourg: at this last siege, though the casualties among the engineers were very great., the operations were conducted under the directions of Cormon taingne with the utmost regularity ; and it is stated, as an example of the precision with which he formed hie plans, that all the operations on the ground were exactly conformable to the written instructions which he drew up and to the sketches which accompanied them.
Subsequently to that time he was employed in inspecting the forti fications of the kingdom, from the Rhone to Calais; an% on this occasion, besides a general tract on the manner of fortifying the frontiers of a state, he wrote particular memoirs on the places of Franche Compte, Alsace, and the country between the Moselle and Calais. He was afterwards employed in superintending the construc tions of new works at Strasbourg, Metz, Bitche, and Thionville : at the last of these places he resided, with the rank of Marechal de Camp, and here his useful life terminated.
Cormontaingne wrote several memoirs relating to fortification and other branches of the military art; and that which is on the subject of the attack of fortresses, is said to have been composed, during the siege at which he served, from notes written in the trenches and on the breaches, even under the fire of the enemy. None of his writings were published during his life, except one which, without his know ledge, was printed at the Hague in 1741, under the title of 'Architec ture Militaire; ' and after his death, which occurred on the 20th of October 1752, all his papers were deposited in the Bureau de la Guerre, where they remained above thirty years. Extracts from them were however published, and these served as text-books for the lectures given at the Ecole du Genie, which was established at Mazieres iu 1750. The manuscripts were at length obtained by M. Fo rcroy from the government offices, and were published at Paris by M. Bayart, capitaine du genie, in three volumes 8vo. The first is entitled ' Memorial pour l'Attaque des Places' (1806) ; the second, 'Memorial pour la Defense des Places' (1806); and the third, 'Memo rial pour les Foetifisations permancntes et passagares' (1809). An edition of the first of these works had been published by Bousmard at Berlin in 1803. Cormontaingne did not profess to invent a system of fortification ; but, by certain variations in the constructions, and by additional works, he obviated many defects which are conceived to exist in the systems of Vauban.
(Bousrnard's account of Courmontaingne in the Preface to the JUntorial pour des Places ; Biographic (fairer:elle, kc.)