CHAIN-_shot_. See SHOT. CHALLENGE, a cartel, or invitation to a duel, or other combat; it may with propriety be called a provocation, or summons to fight, when an affront in derogation of honor has been offered. CHALLENGE is also a term applied to an objection made against any member of a court-martial, on the score of real or presumed partiality. The prisoner, however, in this case, must assign his cause of challenge; of the relevancy, or validity of which the members are themselves the judges; so that peremptory challenges, though allowed in civil cases, are not acknowleged in military law. The privilege of challenging belongs equally to the prisoner and the prosecutor. CHAMADE, in a military sense, means a signal made by the enemy, either by beat of drum, or sound of trumpet, when they have any matter to propose; such as to bury their dead, &c. See PARLEY. CHAMBER _of a cannon_, in artillery, that part of the bore of a cannon which receives the powder with which it is charged. See CANNON. CHAMBER _of a mortar_, the space where the powder lies, and generally of several forms and dimensions, such as the conic, spheric, cylindric, parabolic, and concave, or bottled chambers. See MORTARS. In 1787 and 1789 experiments were made at Woolwich with an 8 inch mortar, with four shifting chambers, to ascertain which form gives the longest range. The chambers were all of the same capacity, viz. 63.7 cubic inches, and contained two pounds of powder. Their forms were: 1st. Common conical chamber with the circular bottom. 2d. The same reversed. 3d. The cylindric chamber with circular bottom. 4th. The spheric chamber. The ranges were the medium of 6 rounds; from them it appears, that when the spheric chamber is filled with powder, it has the advantage in point of range; but when smaller charges are used, its ranges are found to be shorter than those of other forms. The conical (No. 1.) chamber of the present British establishment gives the longest range under other circumstances. CHAMBER _of a mine_, that place where the charge of powder is lodged, to blow up the works over it. See MINE. CHAMBER _of a battery_, is a place sunk under ground for holding powder, loaded shells, and fuzes, where they may be out of danger, and preserved from rain or moisture. CHAMBRER, _faire chambrée_, a military phrase among the French, to signify several persons lodged in the same room, barrack, or tent. CHAMP _de bataille_, _Fr._ field of battle; the ground on which two armies meet. CHAMP _de Mars_, the field of Mars, an open place in the neighborhood of Paris, where troops are frequently reviewed and in which the public festivals have been held. CHAMPION, he who undertook to settle the difference of contending armies, by single combat.