User blog comment:Cyrice1/Stormcloaks or Imperials/@comment-1080767-20120707031447/@comment-1080767-20120708015239

@ Snow x Arrow Actually, if you read The Great War (search "The Great War (Book)" in the wiki), it says near the end that the Emperor chose to flee the Imperial City whilst it was being invaded. His entire main army pushed out in a great exodus as the Emperor and his men fought their way out of the invasion. Some time later, he prepared his forces and reclaimed the capital and ended the war there, while he still had the Imperial City. So no, Cyrodiil is still a part of the Empire, and considering that the book states that "Thalmor leadership committed all available forces to the campaign in Cyrodiil" to sack the Imperial City, it can be assumed that in purging the capital of Thalmor, they also defeated the Thalmor presence in Cyrodiil, or were able to with relative ease before negotiating peace.