After crossing the Russian border on 24 June 1812, Napoleon falsely believed that he would quickly defeat the two main Russian armies. His X corps, under Maréchal Macdonald, was to guard Napoleon’s northern flank, while Prince Karl von Schwarzenberg’s V corps and General Reynier’s VII corps protected the southern flank. After creating two flanking forces, Napoleon divided his Grande Armée into three main groups plus two additional lines, which were to offer protection and provide reinforcements. Napoleon’s commanders were seasoned battlefield generals, apart from Jerôme Bonaparte, Napoleon’s brother-in-law, who ignored Napoleon’s instructions and allowed the Russians to manoeuvre out of danger. Davout, his replacement, blocked General Pyotr Bagration at Mogilev, preventing him from joining the main Russian army at Vitebsk. Bagration retreated to Smolensk where the main Russian army, under Prince Barclay de Tolly, later joined him. From 18 August–24 August Napoleon forced a Russian retreat from Smolensk.
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