Napoleon was an excellent military scientist, he had an understanding and application of the military beyond ordinary people, and would apply various military tactics to actual combat. With this, he led the crippled French army to defeat enemies several times stronger than him in a row. For example, in 1805, Napoleon defeated the French League for the third time, causing heavy losses to Austria, then one of the top five in Europe. In 1807, Napoleon defeated the French League for the fourth time, and the Prussian army was almost completely destroyed, and the national strength was severely damaged. Subsequently, the Russian army was destroyed in Poland, forcing the Russian Tsar Alexander II to negotiate peace with France. Since then, France has undoubtedly become the hegemon of Europe, the top five in Europe has broken three, and britain far abroad is unlikely to pose a threat to the mainland.
In this case, France has been fighting for many years, its own soldiers have long been tired and tired, and there are too many enemies abroad. If Austria and Russia had joined forces, France would have been unlikely to be overwhelmed, let alone a tiger-eyed Britain behind him. If the other four European powers join forces and have at least three times the military strength of France, then France has no chance of winning. So the wisest thing is to find an ally to fight in England together, so as not to have any trouble.
However, Napoleon was carried away by years of victory and became blindly arrogant. It so happened that civil unrest was breaking out in Spain, and France was supposedly not justified in the involvement. But Napoleon not only sent 300,000 elite soldiers to attack, but also made his brother king. Nor in history has there been a rise to the occasion of a foreigner as king, and of course there has been a strong opposition from all strata of Spain, and France has to be plunged into a protracted war.
If Britain could have missed this opportunity to reinforce Spain, France had to move most of its forces south. And in the north of Austria, Prussia, Russia suddenly the pressure was greatly reduced, and it was ready to move. Then, of course, the Fifth Coalition began. An attack was launched in the north. Napoleon, despite the danger, repelled the enemy and forced Austria to cede Vienna.
At this time, France, which should have rested and consolidated its territory, once again did something beyond its own strength. That is to destroy Russia. With the invasion of 670,000 elite soldiers, in the protracted battle, successive defeats were made, and finally only 20,000 people were left.
In 1831, the British took advantage of the victory to pursue and organized Russia, Prussia, and Austria to conduct the Sixth Anti-French Alliance. At this point, France collapsed, and finally Paris was occupied.
Napoleon was defeated, and he did not develop the power to dominate the sea, so that Britain always put a dark arrow behind Napoleon. The second is that too much elite force has been consumed in Spain, but little has been achieved. Third, the level of his men was uneven, and there was no general who could stand alone, so that Napoleon was weak and ran at both ends. Fourth, more importantly, the failure to invade Russia has left France powerless to defend itself. Eventually Napoleon had to concede.