When Le Coq was 13 years old he joined the Saxon infantry. On 30 May 1800 he was appointed a major. In the campaigns of 1806, 1807 and 1809, he fought with distinction; and on 22 February 1810 was promoted to lieutenant-general. In 1812 he received the command of the Saxon Corps marching to Russia. In 1813 he was entrusted with the command of the newly formed Saxon detachments, with whom he fought at the battles of Grossbeeren and Jüterbogk. In 1814 he commanded the Saxon occupation force in the Netherlands. Without his zeal for the return of the captive King Frederick Augustus I of Saxony it is likely that he would have been restored to his throne. With the division of Saxony he was responsible for dividing the army which he accomplished with skill and prudence. After the reconstituted peace of 1815, Le Coq was appointed to the new formation, and made a tremendous contribution to the high command of the army. He died on 30 June 1830 at Brig in the Swiss canton of Valais, on a trip to southern Italy.