On the morning of June 21st Catherine was asleep in the summer house Mon Plaisir at Peterhof. She had been summoned by Peter to attend the feast he had planned for his name day, but the Emperor and his entourage was still at Oranienbaum, another estate of the Imperial family. On this morning in June, Alexis Orlov had slipped past the Holstein Guards and stepped through the open French windows of Catherine's bedroom and awakened her. He quickly told her the plans. Catherine dressed in a few minutes in her simple black mourning dress, and then they were on the way in Orlov's hired hack. Down the road they were met by Gregory Orlov in another hired carriage. It was before eight o'clock in the morning when they arrived at headquarters of the Ismailovsky regiment. Catherine stepped from her carriage to face the soldiers, small and fragile, her mourning dress yellow from the dust of the road. The men knew her by sight as the Grand Duchess or as the Empress, but never like this. Catherine spoke: "I have come to you for protection. The Emperor has given orders to arrest me. I fear he intends to kill me." She said nothing more. The soldiers rushed to kiss her hands, the hem of her dress, and called her their savior. The regimental chaplain, Father Aleksei Razumovskii, came with a cross and started to take the oath. The regimental commander, Count Cyril Razumovsky, appeared and made his way over to Catherine and knelt at her feet. The Ismailovsky 's were hers, and from that moment on, really, so was Russia.

From there they all made their way to the Semenovsky Barracks. Catherine had again driven in her ordinary carriage. More soldiers came to meet them, shouting "Vivat!" Drums rolled, finally the procession reached the Cathedral of Kazan, where they found the church filled with clergy, awaiting her. Catherine walked down the long aisle to the altar, and there she took the oath as Empress and Sole Autocrat. With bells ringing and people shouting, Catherine then proceeded in her shabby carriage to the new Winter Palace, where members of the Senate and the Synod were waiting to swear allegiance. Count Panin, her son's tutor, brought her the child at once. Princess Dashkova finally made her way through the crowds to join Catherine. During the night a manifesto was printed and then distributed to the people in the streets.

"We, Catherine II, It has been clearly apparent to all true sons of our Russian Fatherland that the State of Russia has been exposed to supreme danger by the course of recent events. First, our Greek Orthodox Church has been so shaken, that it was exposed to the most extreme peril: that a heterodox faith might be substituted for our ancient orthodoxy. Second, the glory of Russia, which was carried to such heights by her victorious army at the cost of so much bloodshed, has been trampled underfoot by the conclusion of peace with our most mortal enemy (Frederick II), and the Fatherland had been abandoned to complete subjection, while the internal order, on which the unity and welfare of our entire country depend, has been completely disrupted. For these reasons we have found ourselves compelled, with the help of God, and in accordance with the manifest and sincere desire of our faithful subjects, to ascend the throne as sole and absolute sovereign, whereupon our loyal subjects have solemnly sworn us an oath of allegiance."

Where was Peter? He had left Oranienbaum to go to Peterhof. With him was his mistress Elizabeth Vorontsova, the Prussian Ambassador Baron von Goltz, the Chancellor and many ladies in court attire. A secret messenger had arrived from St. Petersburg with the news that Catherine had been proclaimed Empress. Peter was urged to take his Holsteiners and march on the capital. He refused such confrontation, but he was finally persuaded to go to Kronstadt, a fortified island in the gulf of Finland approximately 12 miles west of St. Petersburg, where Peter had gathered troops for the war he had planned against Denmark. Catherine had already secured Kronstadt through Admiral Talysin, who had been dispatched earlier in the day.

While Peter was sailing towards Kronstadt, Catherine donned a borrowed uniform of the Semenovsky regiment. Before the assembled regiments she swung herself into the saddle astride of the white thoroughbred that had been led up for her. She left a note for the Senate: "Gentlemen of the Senate, I am leaving the city at the head of the army to bring peace and security to the throne. With complete confidence, I entrust to your care my supreme power, the Fatherland, the people and my son." They rode into the northern night, company after company. Finally they stopped at an wretched inn at Krasny Kabak. All needed a rest. At five o'clock in the morning she was informed that someone had come to talk. She found herself face to face with Chancellor Vorontov, who had come on Peter's request. The Chancellor knelt down and swore allegiance. There was no contest between this self-assured woman and the feeble puppet he had left behind. Then they all rode towards Peterhof. Unwilling to fight, Peter signed the act of abdication. The few sentries were easily disarmed. Not a drop of blood had been shed. By order of the Empress, Peter was taken to a nearby estate in the village of Ropsha. There he was held under surveillance. The following day, Sunday, June 30, 1762, Catherine made a triumphal entry into St. Petersburg, where she was greeted with bells ringing, artillery salvos and wild acclamations. Six days later she received the news that Peter had died. He apparently had argued with his guards. It was Alexis Orlov who confessed to her the demise of Peter. Catherine seemed very distressed about his death. Now she had blood on her hands, and she was in no position to punish the culprits. She owed her crown to the Orlovs. On July 7, 1762 she issued a manifesto about Peters death. In accordance with her orders, Peter was interred at the Alexander Nevsky monastery. Catherine did not attend the funeral.