The enemy made contact about thirty miles from Moscow. The supply lines of the Grande Armee stretched out for miles, and were dangerously vulnerable at points. Fighting began on October 5th, 1808, the first official day of the siege of Moscow. Russian cossacks attempted to raid French supplies, and would have succeeded if not for the quick action of General de Caulaincourt. His Dragoons rode to the defense of the wagons, circling them and mounting a defense against the enemy cavalry. So began the phase of the battle known as the Seven Days' Skirmish. Skirmish lines were thrown out and cavalry formed a defensive screen as the army marched onto Moscow. About one thousand were killed or seriously wounded on both sides over the course of those seven days.

The Russian army had swollen in size. At Vilnius they had 200,000 regulars against the roughly 250,000 soldiers of Napoleon's center column. As the Russians had retreated, many of the the peasants, faced with starvation, asked to join. By the time Napoleon reached Moscow, these civilian militia forces had ballooned to more than 800,000 in number, as the people of Russia rallied to fight a great patriotic war against the invaders. Unfortunately, as the Russians knew, and as Napoleon had learned, there was no way to field so many men in one place at one time.

With the French army drawing ever closer to Moscow, Tsar Alexander issued his famous orders. Two Romes had fallen. Moscow was the third-and it must not fall. There would be no more giving of ground. The Russian soldiers, demoralized by having to burn their own homes and fields, rejoiced. There would be no more retreat and no surrender. This was ground to hold or die fighting for.

The first line of defense was near the village of Borodino. The Russian forces had built a series of earthworks between the Moskva and Kolocha rivers. 200,000 Russians, mostly militia, had been assembled to hold the line against the remaining 250,000 men of the French army. The Russian artillery had been deployed heavily to the right. This would prove to be a fatal mistake. The left position was by far the weakest, and Napoleon set out to destroy out. He committed one hundred cannon to bombard the left positions, then sent in a first, unsuccessful assault. When the first attack failed, Napoleon relocated another two hundred cannon to the left and continued bombardment. Time was of the essence, and another unsuccessful attack might bog down the entire assault. Thus, a full 50,000 men were brought to the left and sent forward in an overwhelming advance. With a literal wall of men falling upon them, the untrained militia broke and ran, abandoning the defenses. They would be cut down in the rout. Momentum behind them, they continued to press down the Russian line, bringing them to the Great Redoubt on the Russian right. However, the defenses there were nigh-impenetrable, and for three hours the forces clashed indecisively, with French forces streaming in to reinforce the attack. Many of his surviving officers would be shot dead in the assault.

Napoleon was wary to commit his Imperial Guard, the best and strongest of the Grande Armee, despite the imploring of all of his generals. However, two hours into the attack, one of Old Guard walked brazenly into the generals' meeting. The fighting had clearly stalemated, and the grizzled old grenadier was mad. One of the privileges of the Old Guard was the right to complain, and the man would give Napoleon one of the most severe tongue lashings he would ever receive. The men of the Old Guard were all experienced veterans, many of whom had served Napoleon for almost twenty years. But what use was that bravery if it was never used? What good was a soldier that did not fight? Were the men of the Old Guard selected to enter a retirement? Napoleon relented. Les Grognards were committed.

The presence of the Old Guard stirred the spirits of the men, and the ferocity of the aged troops was something to behold. They stormed the fortifications with no fear of death, and the rain of enemy gunfire all around was no deterrent. Not even literal fire could stop them, for they moved too fast for the heat to catch up. Battles were decided by bayonet as well as by bullet, and that day, the bayonet won. The Great Redoubt fell, and the first line of defense was gone. With it came the capture of 400 pieces of artillery, as most of it could not be retreated with the collapse of the defenses.

Kutuzov was shocked and appalled. He harbored a great love for his soldiers, and feared for their safety. The Tsar had tied his hands. If Kutuzov would not make the sacrifices needed to defend Moscow, someone else would-and Kutuzov would pay the price. Still, it was a deeply scarring thing.

50,000 Russians and 20,000 French had died or were wounded at the first redoubt, with the remainder of the Russians falling back to ridge laying behind the battle. However, the militia became confused when they saw the retreat of the first line, and this soon led to a great drop in morale. When the French came marching, the militia chose to abandon the ridge, and with it, their own safety. Without protection, they too would be run down. The second line had been manned by 50,000, and of those, 20,000 would become casualties of the battle that wasn't. Moscow was now within Napoleon's grasp.

200,000 Russians were guarding the city, along with the 180,000 that retreated from Borodino. For three days, Napoleon's men would sally into the city, and each day they would be pushed back by the sheer volume of men fielded. Fire, which had proven so crucial in previous battles, was failing here, as the Russians were unwilling to destroy their own capital. Moscow had to hold. It was the Third Rome, and there could be no more after. Over the course of those three days, another 45,000 French and 120,000 Russians would die. At the evening of the third day, Napoleon decided to halt the assaults, as he would soon have no army at all. It was decided to use the 1200 cannon to wear down the enemy's resolve. The supplies on hand would have to do. This would've been the end of the matter, if not for one thing.

On the dawn of the 29th day of battle, and the 21st of the siege proper, the plan was interrupted by some of the most devastating and unusual weather ever seen in a military campaign.