On Christmas day 1761, the Empress Elizabeth Petrovna died. The reign of Peter III had begun. Catherine mourned the Empress sincerely. One of Peter's first official actions dealt with stopping the hostilities against Prussia. On April 24, 1762 the new Tsar signed a treaty with the King of Prussia. All occupied territories would be restored to Prussia. He sent a personal letter to the King, assuring him of his friendship. On his finger he wore a ring with a portrait of his idol. The Russian Army had suffered great losses during the Seven Year War. Peter alienated the Army further by trying to impose Prussian discipline and even Prussian uniforms. Amid all this, Catherine heard rumors that Peter intended to dispose of her and make Elizabeth Vorontsova his wife.

A handful of people, among them the Orlov Brothers and some friends, as well as Princess Dashkova, a sister of Peter's mistress, plotted to overthrow the new Tsar. Princess Dashkova, was a young, married lady, very cultured and the complete opposite from her sister. She was also a fervent admirer of Catherine. With all that Peter had done to alienate the Army, the danger in which Catherine found herself, makes it perhaps easier to understand what happened next. On June 27th one of the co-conspirators was arrested. Captain Passek had made insulting remarks about the new Tsar while drinking. The others were afraid of what he may say under torture. The decision was made to act at once.