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 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.

[6][7] 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.

[8] 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 "foreign" faction around Barclay de Tolly, composed mostly of officers of German extraction, advocated the continuation of the present policy of delay and withdrawal to dilute Napoleon's striking power.

Count Matvei Platov's Cossacks imposed a sharp defeat on General Horace Sébastiani's cavalry near Inkovo the same day, inflicting 600 French casualties.

On 8 August, Barclay received false intelligence that Eugène's corps was at Poryeche and reoriented half of his army to face north.

Bagration disobeyed his orders, fearing French Marshal Louis-Nicolas Davout's threat to his left flank.

On 11 August, Barclay stayed put and engaged only in outpost fighting with French cavalry under Neapolitan King Joachim.

This giant force would advance east along the left bank of the Dnieper, swing north to cut the Smolensk-Moscow road and annihilate the isolated Russians.

French engineers under General Jean Baptiste Eblé erected four pontoon bridges across the Dnieper near Rosasna on the night of 13–14 August and by daybreak the 175,000-strong Grande Armée was advancing rapidly toward Smolensk.

This force of 5,500–7,200 infantry, 1,500 cavalry and 10–14 guns was attacked by 20,000 Frenchmen under Murat and Marshal Michel Ney beginning around 2:30 PM on 14 August.

[12] Neverovski requested reinforcements from Bagration and received Nikolai Raevsky's VII Corps, which arrived on the morning of 15 August to defend the southern bank of the Dnieper near Smolensk.

Barclay ordered General Dmitry Dokhturov's corps to join Bagration and directed the Smolensk governor to evacuate the city archives.

With his entire plan of operations hanging in the balance, Napoleon failed to act with sufficient vigor and ordered a 24-hour halt to the advance instead.

[4] Smolensk, a historic fortress city with a population of 12,600, resides along the primary Western route linking Warsaw to Moscow.

The formidable Smolensk Kremlin, encompassed by 38 bastion towers and a sturdy stone wall, served as a significant stronghold.

Napoleon ordered a general assault with three corps of the Grande Armée, supported by two hundred artillery pieces.

French forces lacked ladders or climbing apparatus to scale the city walls and were under counter fire from Russian artillery.

[22]To save the army, Barclay de Tolly abandoned the city destroying all ammunition stores and bridges leaving a small force to hold out for two days to cover his retreat.

[5] The Tsar replaced the unpopular Barclay de Tolly with Kutuzov, who took over the army on 29 August at Tsaryovo-Zaymishche and ordered his men to prepare for battle.