The Reichstag of Gefle, which was opened January 25, 1792, had already greatly disappointed and incensed him, because it had unanimously rejected his demand for an appropriation of ten million dollars which he needed for his new undertaking. The utter disregard of his wishes and the contempt with which his urgent appeals were ignored by the lower order, which had so firmly stood by him in the Reichstag of 1789, showed also his great unpopularity; and the nobility thought that the time had come for striking a bold blow not only to get rid of him, but also to reinstate themselves in power. As we have seen, the moment was very opportune. The public debt was enormous; the distress was general; vague rumors of another war, not against an enemy, but against the rights of the people, were in the air. Then the conspiracy was formed. There were five principal conspirators; and they all belonged to the highest nobility. While some of them had personal grievances, not one of them would have thought of raising his hand against the King, unless a much more important object had been in view. These five were Ankarström, who had already been among the rebellious officers in Finland, Count Ribbing, Count Horn, Count Liliehorn and Baron Pechlin.
The mainspring of the conspiracy was the hope of overthrowing the autocratic system of government, and reinstating the nobility in all its prerogatives. At first the conspirators did not want to resort to murder, but they hoped to be able to abduct the King, compel him to resign, and then to extort from his successor the recognition of those rights and privileges of which Gustavus the Third had deprived them. Having made two or three attempts in that direction, they changed their plan, and concluded that the easiest and safest way to accomplish their aim would be to assassinate the King.
Ankarström volunteered to shoot the King at one of the popular masked balls, which he was in the habit of visiting, and at which he freely mingled with the other visitors. Twice he failed to recognize Gustavus. But the last masquerade of the season at Stockholm was to come off on Friday, March 16, 1792, and Ankarström resolved to make a last effort to strike his victim. And he did, although Gustavus was warned that very evening by one of the conspirators (Count Liliehorn) that it would be dangerous for him to go to the ball, for an attempt would be made on his life. The ball was to come off at the Grand Opera House, and an immense crowd was expected. Four of the conspirators--Pechlin, Ankarström, Horn and Ribbing--took supper together, and afterwards went to the theatre. They wore black dominoes of a uniform pattern, to be able to recognize each other easily. On the other hand, Gustavus had taken supper with one of his closest friends, Count Essen, in a little private room arranged for his use at the theatre itself. During this supper, at ten o’clock in the evening, an anonymous letter was handed to him, written in French and with a lead pencil. The author revealed the whole plot, which, as he asserted, he had learned only during the afternoon. He implored the King not to go to the ball, and to change his conduct and his policy if he wanted to escape assassination. He confessed having opposed the King’s autocratic measures and his _coup d’état_, which he considered illegal and unconstitutional. But, being a man of honor, as he said, the very idea of murder was horrid to him, and he therefore again implored the King to keep away from the ball. This note came from Count Liliehorn. Gustavus read it twice very attentively; but he did not say a word about its contents. He quietly completed his supper and then, accompanied by Count Essen, he proceeded to his box, where he was plainly to be seen by all. It was then only that he showed the note to his companion, who also implored him not to go on the floor among the dancers. Gustavus said he would hereafter put on a coat of mail before going to such places of amusement, but he insisted on going on the floor. They thereupon left the box, put on light dominoes and descended to the floor, which was crowded with a throng of brilliant, gay and grotesque masks.