5 November 1605 fell on a Tuesday, the day the Gunpowder Plot was uncovered beneath the House of Lords.
The plotters intended to destroy Parliament during its state opening and kill King James I, but Guy Fawkes was found guarding the explosives during a late-night search on 4 November. The discovery became public on the following day, 5 November.
The date was recorded in contemporary accounts using the Julian calendar then used in England. Under the modern Gregorian calendar, the weekday remains Tuesday because the calendar reform did not alter the historical weekday sequence for this date in the way it altered dates.
Bonfire Night is observed annually on 5 November, rather than on the date of the search itself, because the failed plot and the king’s survival were commemorated on the day Parliament was due to meet.