and armour. The Roman army supplied 60 to each legion and they were used both offensively during sieges and defensively as part of the Romans' field camp defenses. They were also mounted on ships and carriages to provide support to infantry. Onager The onager was a torsion-powered siege engine in which a sinew or horse hair spring mounted on a wooden frame swung an arm vertically against a stop, hurling projectiles in a high arc. It launched stones from a cup or sling, and it was named after a species of Asiatic ass due to its kick. Buccina A brass instrument used in the ancient Roman army. It was originally designed as a tube measuring some 11 to 12 feet in length, of narrow cylindrical bore, and played by means of a cup-shaped mouthpiece. The tube was bent around upon itself from the mouthpiece to the bell in the shape of a broad C and was strengthened by means of a bar across the curve, which the performer grasped while playing, in order to steady the instrument; the curves over his head or shoulder. The buccina was used for the announcement of night watches and various other announcements in the camp. The instrument is the ancestor of both the trumpet and the trombone. The German word for trombone, Posaune, is derived from buccina. Tribulus A tribulus (caltrop) was a weapon made up of four sharp nails or spines arranged in such a manner that one of them always pointed upward from a stable base (for example, a tetrahedron). Caltrops served to slow down the advance of horses, war elephants, and human troops. It was said to be particularly effective against the soft feet of camels. The late-Roman writer Vegetius, in his work De Re Militari, wrote: Miscellaneous Roman military standards Vexillum Vine staff See also Military of ancient Rome Technological history of the Roman military Notes References Ammianus Marcellinus, Roman History'' (late 4th century) External links Roman military equipment in the British Museum, Hunterian Museum and National Museum of Scotland For images of authentic Roman military equipment see www.romancoins.info Ancient Roman military equipment