Why did Napoleon empire fall?
First French Empire
The alliance arranged at Tilsit was seriously shaken by the Austrian marriage, the threat of Polish restoration to Russia, and the Continental System. The very persons whom he had placed in power were counteracting his plans.  With many of his siblings and relations performing unsuccessfully or even betraying him, Napoleon found himself obliged to revoke their power. Caroline Bonaparte conspired against her brother and against her husband Murat; the hypochondriac Louis, now Dutch in his sympathies, found the supervision of the blockade taken from him, and also the defense of the Scheldt, which he had refused to ensure.  Jérôme Bonaparte lost control of the blockade on North Sea shores. The very nature of things was against the new dynasties, as it had been against the old.