The 1605 conspirators intended to use gunpowder to destroy the House of Lords.
Guy Fawkes was discovered in a cellar beneath the House of Lords during the night of 4 November 1605. He was guarding barrels of gunpowder placed beneath the building as part of the conspiracy’s plan to kill King James I and members of Parliament at the state opening.
Gunpowder was the military explosive available to the plotters; dynamite did not yet exist. The discovery of the material, together with Fawkes’s presence, provided the immediate evidence that exposed the conspiracy.
The gunpowder never detonated. Its failure became the central event remembered by Bonfire Night, although later celebrations focus on fireworks, bonfires and effigies rather than on recreating the original plan.