The phrase “hoisted with one’s own petard” was first referenced by Shakespeare in Hamlet. A petard was a small bomb used to blow breaches in gates or walls. They were bell- or box-shaped boxes of metal or wood which were filled with gunpowder.
The device, usually constructed by engineers, was used by the military forces of all the major European fighting nations by the 16th century. Shakespeare’s reference, therefore, was to seeing an engineer blown up by the bomb he constructed.
Tomorrow, The King’s Speech Rita Bay