Petard

A petard was an early type of explosive device used in siege warfare for breaching walls and gates. It consisted of a metal box or cone filled with gunpowder, attached to a wooden plank or frame. The petard was fixed to the gate or wall intended to be breached, and then ignited with a slow-burning match or fuse.

The force of the explosion was intended to blow a hole, allowing troops to enter the besieged area. However, the use of a petard was notoriously dangerous, both to the defenders and the attackers. The blast was often unpredictable, and the operator was required to be extremely close to the device when it exploded, frequently resulting in severe injury or death.

The phrase "hoist with his own petard" (from Shakespeare's Hamlet) refers to being destroyed or injured by one's own device or plot, and is a metaphorical reference to the dangerous nature of setting off a petard. The etymology of the word is derived from the Middle French petart, itself from peter, meaning "to break wind" or "to explode," highlighting the device's explosive and somewhat unpredictable nature.

The petard was most commonly used in the 16th and 17th centuries, gradually being replaced by more sophisticated and safer explosives and siege techniques.