A lieutenant of the Guards (гвардии поручик) since September 1804, he served with distinction in Battle of Wischau and Battle of Austerlitz, earning combat Order of St. Vladimir for the latter. During the War of the Fourth Coalition, Chernyshev again excelled at Battle of Heilsberg and Battle of Friedland, and was awarded Order of St. George, fourth class, and an honorary Golden Sword for Bravery. However, the coalition lost the battle and the war, and Tsar Alexander settled on diplomacy instead of fighting.