Born a Russian count in 1722, Zakhar Grigoryevich Chernyshev was the older brother of Ivan and Andrei Chernyshev. By 1744, Chernyshev spoke Russian, French, and German. When Princess Sophie of Anhalt-Zerbst was betrothed to Peter III of Russia in 1744, Chernyshev was chosen by Empress Elizabeth of Russia as one of three nobles to join the princess' personal court as a gentleman of the chamber. In 1745, Chernyshev's mother begged Empress Elizabeth to send her son away because she feared his infatuation with the Grand Duchess Catherine Alekseievna of Russia; Chernyshev was given a diplomatic assignment. When he returned to Saint Petersburg six years later, Chernyshev began actively courting the then-grand duchess: flattering Catherine, sending love letters, and finding occasion to recreate with the royal. Chernyshev died unexpectedly on 31 August 1784 in Moscow.
Military
At the age of 13, Chernyshev joined the Imperial Russian Army in 1735, and was promoted to kapitan in 1741. In 1748, he was assigned to a regiment in Moscow, and in 1750, he was promoted to the ranks of polkovnik and general-major. As an Imperial Russian general officer, Chernyshev commanded soldiers in the Seven Years' War. In 1757, he was at the Battle of Kolín, and in 1758, he joined forces with the Austrian army. For his leadership in the 1758 Battle of Zorndorf and the 1760 occupation of Berlin—capital of the Kingdom of Prussia, Chernyshev was awarded the Order of Saint Alexander Nevsky. In early 1762, then-General Chernyshev commanded a Russian corps of 16,000 infantry in Silesia that was attached to the Austrian army, fighting the Prussian kingdom. With the 1762 Treaty of Saint Petersburg, Peter III withdrew from the war and instead threw Russia's lot in with Prussia. Chernyshev was given command of the Russian forces now attached to the Prussian Army, and the Prussian monarch awarded him the Order of the Black Eagle. When Emperor Peter III was replaced by Empress Catherine II later that year on 28 June, one of her first orders was to Chernyshev: immediately return to Russia with his corps, and if King Frederick interfered, "join the nearest army corps of her Imperial Roman Majesty, the empress of Austria." Upon this change in alliances, Catherine II awarded Chernyshev with the Order of St. Andrew. In November 1762, Chernyshev was one of ten military commanders convened by Elizabeth II for the purposes of reforming the Imperial Russian military. Chernyshev retired from the military in early 1764, citing "weak health and straitened finances."
Politics
In 1742, Kapitan Chernyshev was sent to the Holy Roman Empirecity ofVienna, where he worked under the Russian ambassador there, Ludovic Lanczynski. At his mother's urging, Empress Elizabeth next sent Chernyshev as her representative to the sejm of the Polish–Lithuanian Commonwealth in 1745. On 4 March 1764, Catherine II appointed Chernyshev to the College of War's top post of vice-president. He was a Governing Senator in March 1765 when he was awarded by Catherine II for his governmental service. When it first met on 4 November 1768, Chernyshev was on Catherine II's advisory council for the Russo-Turkish War, and in autumn 1773, he was appointed to the new position of War College president, along with a commiserate promotion to General Field Marshal, and advised Catherine II regarding Pugachev's Rebellion. Having lost Catherine II's favor to Lieutenant-GeneralGrigory Potemkin, Chernyshev resigned from the College of War in August 1774.