to handle than the transports, and likely to impress the natives more by their unfamiliar appearance – to be removed a short distance from the others, and then be rowed hard and run ashore on the enemy’s right flank, from which position the slings, bows and artillery could be used by men on deck to drive them back. This manoeuvre was highly successful. Scared by the strange shape of the warships, the motion of the oars, and the unfamiliar machines, the natives halted and then retreated a little. (Caesar, The Conquest of Gaul, p. 99) Siege of Alesia In Gaul, the stronghold of Alesia was under a Roman siege in 52 BC, and surrounded by Roman fortifications. As was standard siege technique at the time, ballistae were placed up in the towers with other soldiers armed with either bows or slings. Onager The onager was a post-classical Roman siege engine, which derived its name from the kicking action of the machine, similar to that of an onager (wild ass). It is a type of catapult that uses torsional pressure, generally from twisted rope, to store energy for the shot. The onager consisted of a frame placed on the ground to whose front end a vertical frame of solid timber was rigidly fixed; through the vertical frame ran an axle, which had a single stout spoke. On the extremity of the spoke was a sling used to launch a projectile. In action the spoke was forced down, against the tension of twisted ropes or other springs, by a windlass, and then suddenly released. The spoke thus kicked the crosspiece of the vertical frame, and the projectile at its extreme end was shot forward. The onagers of the Roman Empire were mainly used for besieging forts or settlements. They would often be loaded with large stones or rocks that could be covered with a flammable substance and set alight. In the Middle Ages (recorded from around 1200 A.D.) a less powerful version of the onager was used that employed a fixed bowl rather than a sling, so that many small projectiles could be thrown, as opposed to a single large one. This engine was sometimes called the mangonel, although the same name may have been used for a variety of siege engines. Scorpio The scorpio was a crossbow-like device that shot smaller arrows with deadly accuracy used both in the field and