On the night of 8 July 1762 in Oranienbaum, she was told her husband had moved against the plot at once. Catherine left the palace, rode to the Izmailovsky Regiment, and asked the soldiers to protect her from Peter III. By the next day she had reached the Semenovsky Barracks, where the clergy stood ready, and she began to reign as Empress of Russia. Peter was arrested, forced to sign his abdication, and eight days later he died at Ropsha, officially of haemorrhoidal colic and apoplexy.

Her beginning was far from the splendour that later clung to her name. She was born on 2 May 1729 in the Ducal Castle at Stettin in Prussian Pomerania, as Princess Sophie Augusta Frederica of Anhalt-Zerbst. Her mother was Joanna Elisabeth, her father Christian August was a Prussian general and governor of Stettin, and her education came chiefly from a French governess and tutors. As a girl she was called a tomboy, and in her own memoirs she wrote of childhood, I see nothing of interest in it.

At fifteen, in 1744, Sophie arrived in Russia and set herself to win over Empress Elizabeth, Alexei Razumovsky, and the Russian court. She learned the language by repeating lessons late at night, survived pneumonia and pleuritis, and on 28 June 1744 converted to Russian Orthodoxy, taking the name Catherine Yekaterina Alekseyevna. On 21 August 1745 she married Peter in the Cathedral of Our Lady of Kazan in St Petersburg. The marriage was unhappy and long unconsummated, but she read Voltaire, Diderot, and Tacitus, and began to think like a ruler who saw hidden motives behind every public act.

That habit of mind mattered when Peter III came to the throne on 5 January 1762. His admiration for Frederick II of Prussia, his halt to the war against Prussia, and his quarrel with Russia’s noble allies left him exposed. Catherine moved quickly. With support from figures such as Grigory Orlov, and later Grigory Potemkin, she seized power in the coup of 1762 and was crowned in Moscow on 22 September 1762 with the Great Imperial Crown, made in only two months by Jérémie Pauzié. The crown, with its 75 pearls and 4,936 diamonds, became the symbol of her new order.

Her reign ran from 1762 to 1796, and it altered the map of Europe. Under generals such as Alexander Suvorov and Pyotr Rumyantsev, and admirals such as Samuel Greig and Fyodor Ushakov, Russia expanded by conquest and diplomacy. She annexed Crimea in 1783, gained land in the Russo-Turkish War of 1768 to 1774, and founded or ordered the founding of Yekaterinoslav, Kherson, Nikolayev, and Sevastopol. In the west she placed Stanislaus Augustus Poniatowski on the Polish throne in 1764, then took part in the partitions of Poland, while in the east Russians became the first Europeans to colonise Alaska.