The army crossed the Niemen river and invaded Russia. The Russians were wise to this move however and did two things to help themselves. Firstly they made an agreement with their ally of Sweden that they would help them in the pending conflict. Sweden would pull out of the conflict with Britain and in return would receive Norway as their own. By pulling out of the war with Britain, Britain could then concentrate on the war with France in Spain, which had been going on for some time. This was of great help towards Russia's chances. This was probably the first example of how allied unity contributed to Napoleon's defeat. Secondly Russia evacuated Moscow, and by the time Napoleon reached it there were only a few civilians and a number of undercover soldiers. These soldiers then set fire to Moscow, which left Napoleon and his huge army standing on the outside of a ruined Moscow waiting for Russia to concede. They didn't concede and Napoleon stayed there in the open until the infamous Russian winter hit them and forced them to retreat.
This was a great example of how Napoleon contributed to his own defeat. His poor planning and his false assumption that Russia would concede cost him 400,000 soldiers, half of whom died during the massive retreat due to the harsh winter which for some reason he forgot came around at that time every year. This was simply bad planning. Napoleon got back to Paris as quickly as he could and raised another 350,000 men, but by than time Russia with the aid of Sweden were invading. The Austrians at this time decided to become neutral for fear of not knowing which side to join. Prussia took more positive steps and decided to join the Russians and Swedes by declaring was on France in march 1813.
This was another example of how allied unity contributed to Napoleon's defeat. With the three nations joining forces they became a much stronger opponent to Napoleon. In August 1813 Austria finally had the courage to make a decision and decided to join Russia and Prussia. They formed a formal alliance in August and in September 1813 Bavaria joined the bandwagon as well. Allied unity was now very strong. In October 1813 the allies went to battle with France in Leipzig, this battle was named the Battle of Nations. The French suffered heavy defeats and were once again forced to retreat. The allied unity was now producing results.
The Battle of Nations saw the beginning of the tumbling of the French structure throughout Europe. In November 1813 Napoleon had to retreat from the Rhine and the other side of France. Britain under the command of Wellington had forced their way through the French border at the Pyrenees and successfully attacked Bayonne. In Holland there was a revolt which saw expulsions of French imperial troops and officers. Napoleon was in real danger of losing everything, he had suffered defeats and was in rapid retreat. It was at this time that Austria offered Napoleon a peace deal that would retain it's borders of 1796. These borders would include Belgium and part of Germany.
Napoleon refused and this is another example of how he contributed to his own defeat. He was in no position to bargain, and yet he still decided to continue fighting. This was brave, but at the end of the day it was the wrong decision. After the rejection of the peace deal the allied forces began invading France in December 1813. This went on till February 1814 when after more defeats for Napoleon, he was offered another peace deal, this time allowing France the borders of 1792. Once again Napoleon refused and that was his last chance. Britain now took the opportunity to join the allies and they all signed an agreement that the war should be fought out to an end. Allied unity was even stronger now, and with Britain on the scene with the allies, the French were defeated again and again.
They were forced to fall back until 1814 when Paris was eventually taken. Wellington at the same time completed his long struggle from Portugal all the way to Bordeaux.Napoleon finally accepted defeat in April 1814 when he signed a treaty which granted him sovereignty over a tiny island in the Mediterranean named Elta Many people felt that this was too mild a decision and their fears became reality when he returned to French soil in March 1815. His name and reputation were still held high and it didn't take him long to rally through France and raise a formidable army. Although slow off the mark the allies quickly assembled an army of considerable size which would easily crush Napoleon's attempt. Napoleon tried to split the allied army using his support in Italy. However the army in Italy was crushed by the Austrians in the first days of May 1815. Napoleon with forces that were well outnumbered decided to head for Belgium for a head to head battle with the allies. he was finally defeated for good this time at Waterloo in June 1815.
Allied unity was not the main factor in the defeat of Napoleon. Certainly it was a major factor, probably the most important factor. They grew stronger as time went on and in the end they were far too powerful for him. However Napoleon himself was also a main factor in his own defeat, he was a brave and good leader, and had more than his fair share of successes. Bad planning in the invasion of Russia, and his obsession for victory however caused him to fail in the end. With odds of no more than 150,000 to750,000 it takes an obsession for victory beyond sanity to go into battle, but he did and he lost. In conclusion allied unity was a major reason for Napoleon's defeat, but also at times he was his own worst enemy.