Why does Great Britain blow up fireworks every year on the 5th of November? Wikipedia knows why:
Guy Fawkes Night, also known as Guy Fawkes Day, Bonfire Night and Firework Night, is an annual commemoration observed on 5 November, primarily in Great Britain. Its history begins with the events of 5 November 1605, when Guy Fawkes, a member of the Gunpowder Plot, was arrested while guarding explosives the plotters had placed beneath the House of Lords. Celebrating the fact that King James I had survived the attempt on his life, people lit bonfires around London, and months later the introduction of the Observance of 5th November Act enforced an annual public day of thanksgiving for the plot’s failure.