petard

Petard comes from Middle French pétard, from péter (to break wind, to fart), from Latin pedere. The connection between this scatological root and an explosive military device is direct: the petard made a loud report when it detonated, and the naming reflects the same vulgar humor that produced words like 'bombard' from 'bombos' (humming, buzzing sound) and would later give English 'bomb.' Medieval and early modern soldiers were not squeamish about naming weapons after body sounds, and the petard's blasting roar invited the association. The word entered English in the late 16th century, carrying its French etymology and its faintly undignified origin, just as the device itself was entering the military engineering vocabulary of European siege warfare.

A petard was a bell-shaped or box-shaped metal or wooden container packed with gunpowder, fitted with a fuse, and designed to be placed against a gate, door, or wall section and detonated to blow an opening. The device was used in siege warfare — specifically in the phase of a siege when a besieging force had managed to approach a gate or breach and needed to make a rapid entry before defenders could respond. The 'petardier' was the specialist who carried the device forward under fire, fixed it to the target using iron hooks or clamps, lit the fuse, and retreated — usually at considerable personal risk, since the petard's effectiveness required positioning close to the blast, and any delay in the fuse or premature detonation was potentially fatal to the operator.

The petard's notorious unreliability — the tendency of the device to explode prematurely, killing the petardier who had placed it — is the basis of Shakespeare's most famous pun, in Hamlet (Act III, Scene 4): 'For 'tis the sport to have the engineer / Hoist with his own petard.' The phrase 'hoist with one's own petard' — meaning to be caught in a trap of one's own making, or to suffer the consequences of one's own scheme — has survived as one of the most durable metaphors in English long after the petard itself became obsolete. Most people who use the phrase today have no idea what a petard was, but the image is exact: the man who set the bomb lifted off the ground by his own explosion, victim of his own technology.

The petard was never a sophisticated weapon — it was a large firecracker applied to a door — and it was displaced as siege engineering developed more reliable and controlled methods of creating breaches in the 17th and 18th centuries. But its brief military career produced one of the most enduring phrases in English, and its etymology remains one of the more memorable in military vocabulary: an explosive named for flatulence, preserved in a metaphor about self-destruction, remembered because a playwright found it useful for a pun. Military history and literary history intersect at odd angles.