Progressing onwards with the previous discussion regarding the origins and history of crossbows, quote €It is not clear exactly where and when the crossbow originated, but there is undoubted evidence that it was used for military purposes from the second half of the 4th century BC onwards. Earliest evidence for the crossbow in Europe dates back to the 5th century BC when the gastraphetes, an ancient Greek crossbow type, appeared. The device was described by the Greek author Heron of Alexandria in his work Belopoeica ("On Catapult-making"), which draws on an earlier account of his famous compatriot engineer Ctesibius (fl. 285€"222 BC). Heron identifies the gastraphetes as the forerunner of the later catapult, which places its invention some unknown time prior to 420 BC. The gastraphetes was a large artillery crossbow mounted on a heavy stock with a lower and upper section, the lower being the case fixed to the bow and the upper being the slider which had the same dimensions as the case.

Meaning "belly-bow", it was called as such because the concave withdrawal rest at one end of the stock was placed against the stomach of the operator, which he could press to withdraw the slider before attaching a string to the trigger and loading the bolt; this could thus store more energy than regular Greek bows. It was used in the Siege of Motya in 397 BC. This was a key Carthaginian stronghold in Sicily, as described in the 1st century AD by Heron of Alexandria in his book Belopoeica. Alexander's siege of Tyre in 332 BC provides reliable sources for the use of these weapons by the Greek besiegers. The efficiency of the gastraphetes was improved by introducing the ballista. Its application in sieges and against rigid infantry formations featured more and more powerful projectiles, leading to technical improvements and larger ballistae.

The smaller sniper version was often called Scorpio. An example for the importance of ballistae in Hellenistic warfare is the Helepolis, a siege tower employed by Demetrius during the Siege of Rhodes in 305 BC. At each level of the moveable tower were several ballistae. The large ballistae at the bottom level were designed to destroy the parapet and clear it of any hostile troop concentrations while the small armor breaking scorpios at the top level sniped at the besieged. This suppressive shooting would allow them to mount the wall with ladders more safely. The use of crossbows in medieval warfare dates back to Roman times and is again evident from the battle of Hastings (1066) until about 1525 AD. They almost completely superseded hand bows in many European armies in the twelfth century for a number of reasons€ end quote.