=Arrest= (_Old Fr._, now _arret_). A French phrase, similar in its import to the Latin word _retinaculum_; it consisted of a small piece of steel or iron, which was formerly used in the construction of fire-arms, to prevent the piece from going off. A familiar phrase among military men in France is, _Ce pistolet est en arret_, “this pistol is in arrest or is stopped.” =Arreste of the Glacis.= Is the junction of the talus which is formed at all the angles. =Arretium.= A city of the Gauls, now in the department of the Yonne, France, where the Gauls defeated the Romans in a bloody battle in 284 B.C. =Arrow.= In fortification, a work placed at the salient angles of the glacis, communicating with the covert way. =Arrow.= A missile weapon of defense, straight, slender, pointed, and barbed, to be shot with a bow. =Arrow-head.= The head of an arrow. =Arrow-wood.= A species of _Viburnum_, from the long straight stems of which the Indians dwelling between the Mississippi and the Pacific make their arrows. =Arrowy.= Consisting of arrows. =Arroyo del Molinos.= A small town in Estremadura, Spain, near the river Guadiana, where Lord Hill, on the 28th of October, 1811, surprised and defeated the French under Gen. Gerard. Nearly 1500 prisoners were taken, including Prince d’Aremburg, Gen. Brun, one colonel, two lieutenant-colonels, a commissaire de guerre, and no less than 30 captains and inferior officers. It was altogether a most brilliant achievement. =Arsenal.= A public establishment for the storage or for the manufacture and storage of arms and all military equipments, whether for land or naval service. In the United States there are 17 arsenals and 1 armory (Springfield, Mass.), situated at different points throughout the whole country convenient for the distribution of _materiel_, as follows: Alleghany arsenal, at Pittsburg, Pa.; at Augusta, Ga.; Benicia, Cal.; Fort Monroe, Va.; Fort Union, N. M.; Frankford arsenal, Philadelphia, Pa.; Indianapolis, Ind.; Kennebec arsenal, Augusta, Me.; New York; Pikesville, Md.; Rock Island, Ill.; Jefferson Barracks, Mo.; San Antonio, Texas; Vancouver, W. T.; Washington, D. C.; Watertown, Mass.; and Watervliet arsenal, West Troy, N. Y. =Arsouf= (Syria). At a battle here Richard I. of England, commanding the Christian forces, reduced to 30,000, defeated Saladin’s army of 300,000 and other infidels on September 6, 1191. Ascalon surrendered, and Richard marched to Jerusalem, 1192. =Art, Military.= Military art may be divided into two principal branches. The first branch relates to the order and arrangement which must be observed in the management of an army, when it is to engage an enemy, to march, or to be encamped. This branch is called _tactics_. The same appellation belongs to the other branch of military art, which also includes the composition and application of warlike machines. See LOGISTICS, STRATEGY, STRATAGEM, TACTICS, and WAR.