Unluckily for the conspirators, they had more courage than prudence. Eighteen of the younger men were, on the night fixed, amusing themselves with drinking in a public-house, and talked with such freedom that the hostess discovered their secret. She told a friend that the party consisted of some young gentlemen who were having their hair powdered in order to go to an attack on the castle. Arthur, the originator of the enterprise, also made what proved to be a dangerous revelation. He engaged his brother, a doctor, in the scheme. The brother grew so nervous and low-spirited that his wife, seeing that something was amiss with him, gave him no rest until he had revealed the secret. She, perhaps to save her husband, perhaps from Whig proclivities, instantly sent an anonymous letter to Sir Adam Cockburn, lord justice-clerk of Edinburgh, apprising him of the plot. He at once sent the intelligence to the castle. His messenger reached there at a late hour, and had much difficulty in gaining admittance. When he did so, the deputy-governor saw fit to doubt the improbable tidings sent him. The only precaution he took was to direct that the rounds and patrols should be made with great care. With this provision for the safety of the castle, he went to bed, doubtless with the comfortable feeling that he had done all that could be expected of a reasonable man in so improbable a case.
While this was going on, the storming-party had collected at the church-yard of the West Kirk, and from there proceeded to the chosen place at the foot of the castle walls. There had been a serious failure, however, in their preparations. They had with them a part of the rope-ladders on which their success depended, but he who was to have been there with the remainder—Charles Forbes, an Edinburgh merchant, who had attended to their making—was not present, and they awaited him in vain.
Without him nothing could be done; but, impatient at the delay, the party made their way with difficulty up the steep cliff, and at length reached the foot of the castle wall. Here they found on duty one of the sentinels whom they had bribed; but he warned them to make haste, saying that he was to be relieved at twelve o'clock, and after that hour he could give them no aid.
The affair was growing critical. The midnight hour was fast approaching, and Forbes was still absent. Drummond, the leader, had the sentinel to draw up the ladder they had with them and fasten it to the battlements, to see if it were long enough for their purpose. He did so; but it proved to be more than a fathom short.
And now happened an event fatal to their enterprise. The information sent the deputy-governor, and his direction that the patrols should be alert, had the effect of having them make the rounds earlier than usual. They came at half-past eleven instead of at twelve. The sentinel, hearing their approaching steps, had but one thing to do for his own safety. He cried out to the party below, with an oath,—
"Here come the rounds I have been telling you of this half-hour; you have ruined both yourselves and me; I can serve you no longer."
With these words, he loosened the grappling-irons and flung down the ladders, and, with the natural impulse to cover his guilty knowledge of the affair, fired his musket, with a loud cry of "Enemies!"
This alarm cry forced the storming-party to fly with all speed. The patrol saw them from the wall and fired on them as they scrambled hastily down the rocks. One of them, an old man, Captain McLean, rolled down the cliff and was much hurt. He was taken prisoner by a party of the burgher guard, whom the justice-clerk had sent to patrol the outside of the walls. They took also three young men, who protested that they were there by accident, and had nothing to do with the attempt. The rest of the party escaped. In their retreat they met Charles Forbes, coming tardily up with the ladders which, a quarter of an hour earlier, might have made them masters of the castle, but which were now simply an aggravation.
It does not seem that any one was punished for this attempt, beyond the treacherous sergeant, who was tried, found guilty, and hanged, and the deputy-governor, who was deprived of his office and imprisoned for some time. No proof could be obtained against any one else.
As for the conspirators, indeed, it is probable that the most of them found their way to the army of the Earl of Mar, who was soon afterwards in the field at the head of some twelve thousand armed men, pronouncing himself the general of His Majesty James III.,—known to history as the "Old Pretender."