CORPS _de garde_, _Fr._ an inferior post which is sometimes covered in, and at others is in the open air, garrisoned and defended by troops who are occasionally relieved, and whose immediate duty is to prevent a post of greater consequence from being surprised. _Corps de garde_, in the French acceptation of the word, signifies not only the place itself, but likewise the men who are stationed to protect it. CORPS _de garde avancés_, _Fr._ These posts are occupied by cavalry and infantry, according to the exigency of the service, and the peculiar nature of the ground. When a camp is secured by entrenchments, and has one line of defence, the corps de garde, or advanced post of the cavalry is on the outside of the line, and each part has its quarter and main guard. These guards are always within sight of the same line, unless the unevenness of the ground should obstruct the view. The quarter guard or petit corps de garde is more in front, but still in sight of the main guard, and the _vedette_ is still further in advance for the security of both. CORPS _de battaille_, _Fr._ the main body of an army, which marches between the advanced and the rear guard. CORPS _de reserve_, See REAR GUARD. CORRESPOND, an officer or soldier who corresponds with the enemy, is liable to suffer death, by the articles of war. CORSAIR, in naval history, a name given to the piratical cruisers of Barbary, who frequently plunder the merchant ships of countries with whom they are at peace. CORSELET, a little cuirass; or according to others, an armor, or coat made to cover the whole body, anciently worn by the pike-men, who were usually placed in the fronts and flanks of the battle, for the better resisting the enemy’s assaults, and guarding the soldiers posted behind them. COSECANT, the secant of an arch which is the complement of another to 90°. COSINE, the right sine of an arch which is the complement of another to 90°. COSSACS, in military history, a wild irregular people, who inhabit the Ukraine, and live by plunder and piracy, in small vessels on the Black Sea. A scythe fixed on the end of a pole was their ancient weapon. They are now a regular militia, and use the same arms as the Croats and Pandours. COTANGENT, the tangent of an arch which is the complement of another to 90°. COTE _extérieur du poligone_, _Fr._ exterior side of the polygon. The line which is drawn from the capital of one bastion to another. COTE _intérieur du poligone_, _Fr._ interior side of the polygon. The line which is drawn from the angle of one gorge to the angle of the gorge most contiguous to it. See sides of the POLYGON. COUNCIL _of war_, in military affairs, is an assembly of principal officers of an army or fleet, called by the general or admiral who commands, to concert measures for their conduct. COUNTER-APPROACHES, lines or trenches made by the besieged, when they come out to attack the lines of the besiegers in form.