User blog comment:AveryWood/Reasons Why Going With the Empire is Better/@comment-1786741-20120817053847/@comment-194.22.5.16-20120817120713

But the empire could have dropped Skyrim as an imperial province (see Hammerfell for precedence), and then the treaty would not apply to Skyrim and there'd be no civil.

But the empire choose instead to attack their fellow Men at the behest of elves.