Nov 5th is celebrated as Guy Fawkes Day in the UK. These days many people simply call it “Bonfire Night” and in truth that is probably a better name for it.
The burning of bonfires was, and in Ireland still is, a tradition associated with Halloween. Celebrated on Oct 31st in Ireland the original feast of halloween was the Celtic Pagan New Year. The feast was celebrated on the third harvest. Harvest 1 is the grain (Lughnasa) involving summer bonfires. Harvest 2 (Fomhair) is the fruits, nuts and vegetables. Harvest 3 is Samhain, the blood harvest, when the breeding stock were selected for over-wintering and the losers were slaughtered and preserved. You can see how all this flowing blood translated into our modern view of Halloween.
The Christian church did its best to transmogrify pagan rituals into Christian counterparts. One area where the Catholic church failed utterly was with Halloween. It persisted as a pagan celebration despite the best efforts of the church.
In England the protestants had better luck subverting the pagan rites. Two events contributed to this. Firstly the Gunpowder Plot when Catholic rebels tried to blow up the houses of parliament on Nov 5th 1605. The Catholic rebel Guy Fawkes was found in possession of the gunpowder, was arrested and tortured. Sentenced to be hanged, drawn and quartered he avoided that terrible end by leaping from the scaffold and breaking his neck.
Fawkes became a protestant symbol for the catholic rebels, a convenient whipping boy. Effigies of Fawkes were burned on the Halloween bonfires, making it a more protestant celebration than heretofore. However, given the puritan nature of Protestantism at that time we must question how overt these celebrations could be,
Nov 5th became solidified as bonfire night when William of Orange landed in England on Nov 5th 1688 launching the Glorious Revolution. Bonfires greeted William in his progress through the land, and the more relaxed mores of Britain permitted overt celebrations.
In Northern Ireland, by contrast, the bonfires are lit on the 12th of July, when William arrived there.