Gastraphetes The gastraphetes ( from Ancient Greek γαστραφέτης , English translation : " belly - releaser " ) was a hand - held crossbow used by the Ancient Greeks . It was described in the 1st century AD by the Greek author Heron of Alexandria in his work " Belopoeica " , which draws on an earlier account of the famous Greek 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 399 BC . Unlike later Roman and medieval crossbows , spanning the weapon was not done by pulling up the string , but by pushing down an elaborate slider mechanism . Description . A fairly detailed description and drawing of the gastraphetes appears in Heron ' s " Belopoeica " ( Ancient Greek Βελοποιικά , English translation : " On arrow - making " ) , drawn from the account by the 3rd - century BC engineer Ctesibius . The weapon was powered by a composite bow . It was cocked by resting the stomach in a concavity at the rear of the stock and pressing down with all strength . In this way considerably more energy can be summoned up than by using only one arm of the archer as in the hand - bow . There are no attestations through pictures or archaeological finds , but the description by Heron is detailed enough to have allowed modern reconstructions to be made . According to some authors , the dimensions of the gastraphetes may have involved some kind of prop . A larger version of the gastraphetes were the oxybeles , which were used in siege warfare . These were later supplanted by the early ballista e that later also developed into smaller versions supplanting also the gastraphetes . Date . According to a long dominant view expressed by E . W . Marsden , the gastraphetes was invented in 399 BC by a team of Greek craftsmen assembled by the tyrant Dionysius I of Syracuse . However , recent scholarship has pointed out that the historian Diodorus Siculus ( fl . 1st century BC ) actually did not mention the gastraphetes , but was referring to the invention of the " katapeltikon " , a mechanical arrow firing catapult . Since Heron states in his " Belopoeica " that stand - mounted mechanical artillery such as the " katapeltikon " was inspired by the earlier hand - held gastraphetes , the invention of handheld crossbows into Greek warfare must have thus occurred some unknown time before 399 BC . The terminus ante quem may be more precisely defined as being before 421 BC , since another Greek author , Biton ( fl . 2nd century BC ) , whose reliability has been positively reevaluated by recent scholarship , credits two advanced forms of the gastraphetes to a certain Zopyros . This Zopyros was probably a Pythagorean engineer from southern Italy . He may have designed his stand - mounted bow - machines on the occasion of the sieges of Cumae and Milet between 421 BC and 401 BC , thus marking the date by which the archetypical gastraphetes must have already been known . Other ancient crossbows . Besides the gastraphetes , the ancient world knew a variety of mechanical hand - held weapons similar to the later medieval crossbow . The exact terminology is a subject of continuing scholarly debate .