 Complete the following phrase:  In 1815 the Russian-German Legion became integrated into the Prussian Army and Clausewitz re-entered Prussian service as a colonel. He was soon appointed chief-of-staff of Johann von Thielmanns III Corps. In that capacity he served at the Battle of Ligny and the Battle of Wavre during the Waterloo Campaign in 1815. An army led personally by Napoleon defeated the Prussians at Ligny south of Mont-Saint-Jean and the village of Waterloo on 16 June 1815, but they withdrew in good order. Napoleons failure to destroy the Prussian forces led to his defeat a few days later at the Battle of Waterloo 18 June 1815, when the Prussian forces arrived on his right flank late in the afternoon to support the Anglo-Dutch-Belgian forces pressing his front. Napoleon had convinced his troops that the field grey uniforms were those of Marshal Grouchys grenadiers. Clausewitzs unit fought heavily outnumbered at Wavre 1819 June 1815, preventing large reinforcements from reaching Napoleon at Waterloo. After the war, Clausewitz served as the director of the Kriegsakademie, where he served until 1830. In that year he returned to active duty with the army. Soon afterward, the outbreak of several revolutions around Europe and 