Baron von Steuben joined the Prussian Army at age 17. He served as a second lieutenant during the Seven Years' War in 1756, and was wounded at the 1757 Battle of Prague. He served as adjutant to the free battalion of General Johann von Mayr and was promoted to first lieutenant in 1759. In August 1759 he was wounded a second time at the Battle of Kunersdorf. In the same year, he was appointed deputy quartermaster at the general headquarters. In 1761 he became adjutant of the Major General Von Knobloch upon being taken prisoner by the Russians at Treptow. He subsequently attained the rank of captain, and served as aide-de-camp to Frederick the Great; in 1762 he was one of 13 young officers chosen to participate in a special course of instruction delivered by the king himself.