The Battle of Smolensk was the first major battle of the French invasion of Russia. It took place on 16–18 August 1812 and involved about 45,000 men of the Grande Armée under Emperor Napoleon I against about 30,000 Russian troops under General Barclay de Tolly. Napoleon occupied Smolensk by driving out Prince Pyotr Bagration's Second Army. The French artillery bombardment burned the city to the ground. Of 2,250 buildings, 84% were destroyed with only 350 surviving intact. Of the city's 15,000 inhabitants, about 1,000 were left at the end of the battle inside the smoking ruins. With over 15,000 casualties, it was one of the bloodiest battles of the invasion. Prelude Vitebsk operation The Russian First Western Army under General Michael Andreas Barclay de Tolly slipped away from Vitebsk on 27 July after an inconclusive fight against Emperor Napoleon, avoiding a general engagement. Napoleon was frustrated by his inability to bring the Russian army to battle and lingered at Vitebsk until 12 August to reform his Grande Armée and wait for stragglers to catch up. General Jean-Andoche Junot replaced King Jérôme as commander of the Westphalian VIII Corps and the Corps joined Napoleon's main army on 4 August near Orsha. French situation After five weeks of non-stop operations, the main 375,000-man strike force available to Napoleon had been reduced to 185,000 men by a host of factors. 90,000 troops under Marshal Nicolas Oudinot and Generals Laurent de Gouvion Saint-Cyr, Jean Reynier and Victor de Fay de La Tour-Maubourg had been detached for various missions. Russian forces had inflicted thousands of combat losses on Napoleon's main army, but the primary cause in the reduction of his force was strategic consumption—the need to garrison cities, towns, fortresses and forward supply depots. Rapid forced marches and the inability of supply wagon trains led to high incidences of desertion and tens of thousands of losses to hunger and disease, most notably dysentery. The scorching July heat reduced the availability of water supplies. Huge numbers of cavalry horses and transportation horses and oxen had died due to a lack of grazing areas and the inability of the wagons to carry enough fodder. Russian plan The loss of vast stretches of Russian territory to the advancing French led to a crisis and shift in power in the Russian high command. An aggressive "Russian" faction around Prince Pyotr Bagration called for an immediate, all-out attack against Napoleon.