Pitty you don't know more about this great countryman of yours.
Clausewitz entered the Prussian military service at the age of twelve years as a Lance-Corporal, eventually attaining the rank of Major-General. He served in the Rhine Campaigns (1793–1794) e.g. the Siege of Mainz, when the Prussian army invaded France during the French Revolution, and later served in the Napoleonic Wars from 1806 to 1815. Clausewitz served during the Jena Campaign. Clausewitz, serving as Aide-de-Camp to Prince August, was captured in October 1806 when Napoleon invaded Prussia and defeated the massed Prussian-Saxon army commanded by Karl Wilhelm Ferdinand, Duke of Brunswick (who was mortally wounded), in twin battles at Jena and Auerstedt (see Battle of Jena-Auerstedt) on October 14, 1806.
Opposed to Prussia's enforced alliance to Napoleon, he left the Prussian army and subsequently served in the Russian army from 1812 to 1813 during the Russian Campaign. Like many Prussian officers living in Russia, he joined the Russo-German Legion in 1813. In the service of the Russian Empire, Clausewitz helped negotiate the Convention of Tauroggen (1812), which prepared the way for the coalition of Prussia, Russia, and the United Kingdom that ultimately defeated Napoleon I of France and his allies.
In 1815, the Russo-German Legion was integrated into the Prussian Army and Clausewitz thus re-entered Prussian service. He was soon appointed chief of staff to Johann von Thielmann's III Corps. In that capacity, he served at the Battle of Ligny and the Battle of Wavre during the Waterloo Campaign in 1815. The Prussians were defeated at Ligny (south of Mont-Saint-Jean and the village of Waterloo) by an army led personally by Napoleon, but Napoleon's failure to actually destroy the Prussian forces led to his eventual defeat a few days later at the Battle of Waterloo when the Prussian forces arrived on his right flank late in the afternoon and joined the Anglo-Dutch forces pressing Napoleon's front. At Wavre, Thielmann's corps, greatly outnumbered, prevented Marshall Grouchy from reinforcing Napoleon with his corps.
Clausewitz was promoted to Major-General in 1818 and appointed director of the Kriegsakademie, where he served until 1830. In the latter year, the outbreak of several revolutions around Europe and a crisis in Poland appeared to presage another major European war. Clausewitz was appointed chief-of-staff to the only army Prussia was able to mobilize, which was sent to the Polish border. He subsequently died in a cholera outbreak in 1831. His magnum opus on the philosophy of war was written during this period, and was published posthumously by his widow in 1832.
