The origin of this celebration stems from events which took place in 1605 and was a conspiracy known as "The Gunpowder Plot," intended to take place on November 5th of that year (the day set for the opening of Parliament). Also known as "Firework Night" and "Bonfire Night," November 5th was designated by King James I (via an Act of Parliament) as a day of thanksgiving for "the joyful day of deliverance." This Act remained in force until 1859. On the very night of the thwarted Gunpowder Plot, it is said that the populace of London celebrated the defeat by lighting fires and engaging in street festivities. It would appear that similar celebrations took place on each anniversary and, over the years, became a tradition. In many areas, a holiday was observed, although it is not celebrated in Northern Ireland (Wikipedia).