The weakest parts of the plot were the arrangements for the subsequent rebellion which would have swept the country and installed a Catholic monarch. Due to the requirements for money and arms, Sir Francis Tresham was eventually admitted to the plot, and it was probably he who betrayed the plot in writing to his brother-in-law Lord Monteagle. An anonymous letter revealed some of the details of the plot; it read: "I advise you to devise some excuse not to attend this parliament, for they shall receive a terrible blow, and yet shall not see who hurts them".
According to the confession made by Fawkes on Tuesday 5 November 1605, he had left Dover around Easter 1605, bound for Calais. He then travelled to Saint-Omer and on to Brussels, where he met with Hugh Owen and Sir William Stanley before making a pilgrimage to Brabant. He returned to England at the end of August or early September, again by way of Calais.
Guy Fawkes was left in charge of executing the plot, while the other conspirators fled to Dunchurch in Warwickshire to await news. Once Parliament had been destroyed, the other conspirators planned to start a revolt in the Midlands.
During the preparation, several of the conspirators had been concerned about the safety of fellow Catholics who would be present in Parliament on the day of the planned explosion. On the evening of Friday, 26 October Lord Monteagle received an anonymous letter while at his house in Hoxton.
Monteagle had the note read out loud, possibly to warn the plotters that the secret was out, and promptly handed it over to Robert Cecil, 1st Earl of Salisbury, the Secretary of State. The conspirators learned of the letter the following day, but decided to go ahead with their plan, especially after Fawkes inspected the undercroft and found that nothing had been touched.
Having been shown the letter, the King ordered Sir Thomas Knyvet to conduct a search of the cellars underneath Parliament, which he did in the early hours of 5 November. Shortly after midnight, Fawkes was found leaving the cellar the conspirators had rented and was arrested, giving his name as John Johnson. Inside, the barrels of gunpowder were discovered hidden under piles of firewood and coal. Far from denying his intentions during the arrest, Fawkes stated that it had been his purpose to destroy the King and the Parliament. Nevertheless, Fawkes maintained his false identity and continued to insist that he was acting alone. Later in the morning, before noon, he was again interrogated. He was questioned on the nature of his accomplices, the involvement of Thomas Percy, what letters he had received from overseas and whether or not he had spoken with Hugh Owen.
A letter written by Gentleman of the Bedchamber, Sir Edward Hoby gave details of all those that would have been caught in the explosion:
On 5 November we began a Parliament, to which the King should have cometh in person, but refrained through a practice but that morning discovered. The plot was to have blown up the King at such time as he should have been sat in his royal throne, Nobility and Commons and with all Bishops, Judges and Doctors at one instant, and the blast to have ruined the whole estate and kingdom of England.
Fawkes was taken to the Tower of London and interrogated there under torture. Torture was forbidden, except by the express instruction of the monarch or a body such as the Privy Council or the Star Chamber. In a letter of 6 November, King James I stated:
The discovery of the Gunpowder Plot aroused a wave of national relief at the delivery of the king and his sons, and inspired in the ensuing parliament a mood of loyalty and goodwill, which Salisbury astutely exploited to extract higher subsidies for the king than any (bar one) granted in Elizabeth's reign. In his speech to both Houses on 9 November, James expounded on two emerging preoccupations of his monarchy: the Divine Right of Kings and the Catholic question. He insisted that the plot had been the work of only a few Catholics, not of the English Catholics as a whole, and he reminded the assembly to rejoice at his survival, since kings were divinely appointed and he owed his escape to a miracle.
On hearing of the failure of the plot, the conspirators fled towards Huddington Court near Worcester, a family home of Thomas and Robert Wintour. Heavy rain, however, slowed their travels. Many of them were caught by Richard Walsh, the Sheriff of Worcestershire, when they arrived in Stourbridge.
The remaining men attempted a revolt in the Midlands. This failed, coming to a dramatic end at Holbeche House in Staffordshire, where there was a shoot-out resulting in the deaths of Catesby and Percy and capture of several other principal conspirators. Jesuits and others were then rounded up in other locations in Britain, with some being killed by torture during interrogation. Robert Wintour managed to remain on the run for two months before he was captured at Hagley Park.
The conspirators were tried on 27 January 1606 in Westminster Hall. All of the plotters pleaded "Not Guilty" except for Sir Everard Digby, who attempted to defend himself on the grounds that the King had reneged on his promises of greater tolerance of Catholicism. Sir Edward Coke, the attorney general, prosecuted, and the Earl of Northampton made a speech refuting the charges laid by Sir Everard Digby. The trial lasted one day (English criminal trials generally did not exceed a single day's duration) and the verdict was never in doubt.
The trial ranked highly as a public spectacle, and there are records of up to 10 shillings being paid for entry. Four of the plotters were executed in St. Paul's Churchyard on 30 January. On 31 January, Fawkes, Winter and a number of others implicated in the conspiracy were taken to Old Palace Yard in Westminster, in front of the scene of the intended crime, where they were to be hanged, drawn and quartered.
Fawkes, although weakened by torture, cheated the executioners: when he was to be hanged until almost dead, he jumped from the gallows, breaking his neck and killing himself, thus avoiding the gruesome latter part of his execution.
Henry Garnet was executed on 3 May 1606 at St Paul's. His crime was of being the confessor of several members of the Gunpowder Plot, and as noted, he had opposed the plot. Many spectators thought that his punishment was too severe. Antonia Fraser writes:
Due to the Gunpowder Plot, many Catholics found themselves persecuted or imprisoned in the Tower of London, including the following:
Greater freedom for Catholics to worship as they chose seemed unlikely in 1604, but after the plot in 1605, changing the law to afford Catholics leniency became unthinkable; Catholic Emancipation took another 200 years. Nevertheless, many important and loyal Catholics retained high office in the kingdom during King James' reign.
Interest in the demonic was heightened by the Gunpowder Plot. The king himself had become engaged in the great debate about other-worldly powers in writing his "Daemonology" in 1597, before he became King of England as well as Scotland. The apparent devilish nature of the gunpowder plot also partly inspired William Shakespeare's "Macbeth". Demonic inversions (such as the line "fair is foul and foul is fair") are frequently seen in the play. Another possible reference made in Macbeth was to equivocation, as Henry Garnett’s "A Treatise of Equivocation" was found on one of the plotters, and a resultant fear was that Jesuits could evade the truth through equivocation:
Faith, here's an equivocator, that could
Swear in both the scales against either scale;
Who committed treason enough for God's sake,
Yet could not equivocate to heaven
- Macbeth, Act 2 Scene 3