On the night of November 4th 1605, Guy Fawkes was caught guarding 36 barrels of gunpowder in a cellar beneath the Houses of Parliament. If not for an anonymous tip-off, he and his accomplices would have decimated the building, including Westminster Hall and the Abbey, killed King James I, and transformed how we see London today.
The Roman Catholic conspirators opposing the lack of religious tolerance under the Protestant king came together to form the Gunpowder Plot: they planned to assassinate James by blowing up the House of Lords during the State Opening of Parliament, kickstarting a series of actions across England that would lead to the installation of James' daughter Elizabeth as a new Catholic head of state.
The plan failed when the conspirators were betrayed. Fawkes and seven others were tried and convicted of treason and executed in January 1606. His head was among those displayed on pikes at London Bridge. Celebrating that the king had survived, people lit bonfires around London; and in the aftermath, Parliament declared November 5th a national day of thanksgiving. It was made illegal not to join in the celebrations, and the act remained in force until 1959.
Today, Guy Fawkes Day is celebrated in the United Kingdom and a number of countries that were formerly part of the British Empire, with parades, fireworks, bonfires, and food. Straw effigies of Fawkes are tossed onto the bonfire, as well as in more recent years, contemporary political figures. Traditionally, children carried these “Guys” through the streets in the days leading up to Bonfire Night to ask passersby for “a penny for the guy,” often reciting rhymes associated with the occasion, the best known of which dates from the 18th century:
Remember, remember, the fifth of November
Gunpowder treason and plot
We see no reason
Why Gunpowder treason
Should ever be forgot
The Yeomen of the Guard also perform an annual search of Parliament to check for potential arsonists, although it is more ceremonial than serious. And the lantern that Guy Fawkes himself was carrying when he was arrested in the cellars of Parliament was transferred to the Ashmolean Museum in Oxford, where it can still be seen today.
References:
https://www.sykescottages.co.uk/blog/fun-facts-for-bonfire-night/