De gastraphetes is een zware kruisboog die vanaf 400 BC door de Oud-Grieken werd gebruikt. Bij een normale handboog kan een boogschutter deze niet lang gespannen houden. Ook is er een bovengrens aan de maximale lengte en kracht van de boog door dat de pees niet verder dan een armlengte naar achter kan worden getrokken. Bij de gastraphetes is de boog langer en krachtiger doordat de boogschutter de boog spant met zijn gewicht in plaats van met zijn arm. De achterzijde van het kruishout van de kruisboog is U-vormig waardoor de schutter door er met zijn de buik op te gaan leunen / duwen deze spant. Daarom heet de gastraphetes ook wel " buikboog ". Het kruishout heeft pallen aan weerskanten zodat de boog gespannen bleef. De gastraphetes vuurt een houten kruisboogpijl in een vlakke baan.

The gastraphetes was a large stock siege crossbow used by the Ancient Greeks. It was described in the first century AD by the Greek author Heron of Alexandria in his work Belopoeica.  It is believed to have been invented around 400 BC.The bow was made out of a layer of horn, wood and animal sinew. With a normal bow the power stored in the bow couldn't be held by the archer for long. He also couldn't fire a bow that was too large, because he then wouldn't be able to pull back the bowstring. In the Gastraphetes, the bow was larger and had more power stored in it because the archer would span the bow by using it's own weight, rather then it's hands. Therefor an U-shaped extension was made at the back end of the bow, where the archer would rest his belly on (that's why it's also called a "belly-bow"). The slider had a ratchet on both sides of the bow, which prevented the bow from firing when the archer took his weight of it. This was a far better and easier way to span the bow, and the bow could be made bigger and stronger, increasing the distance an arrow could be shot.

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.

The Gastraphetes, a form of primitive crossbow that fired a wooden bolt on a flat trajectory along a slot in the aiming rod. Main components (syrinx / pipe and diostra / slider). Could reach a bow length of 15 feet and could fire a stone of 40 pounds some 200 to 300 yards. Mainly known from Heron of Alexandria references. It was used successfully during the siege of Motya, a Carthaginian island fortress on the west end of Sicily, in 397 BC and Greek engineers improved further the capabilities of the device reaching its physical limitations. The army of Dionysius I surprised the Carthaginias with the newly developed gastraphetes with its larger range. The desciption of Heron of Alexandria is based on an older by Ctesibius.

Die Armbrust war den Römern unter der griechischen Bezeichnung Gastraphetes (Brustspanner) schon lange bekannt. Doch trotz der großen Durchschlagskraft der von ihr verschossenen Bolzen war sie als Infanteriewaffe nie sonderlich beliebt, denn sie war schwer, unhandlich und das Spannen war aufwendig. Erst zur Zeit Rufus' II., gegen 508, wurde ein verbessertes Modell konstruiert, das in der Folgezeit bei den Legionen eingeführt wurde und seit Mitte des 6. Jahrhunderts zur Standardausrüstung der weströmischen Armee gehört.


Charybdis - Gastraphetes