This is one thing I really like. The side which is controlling Skyrim will fortify their situation in holds. It's nice to clear forts from bandits and other unfriendly beings and see that in a few days Stormcloak soldiers will move in the fort you have cleared. It makes me want to clear every fort.

i have not noticed any garrison of any forts after completing the war... is it just any fort or are you talking about the forts you liberate in the quests? cause ive cleared lotsa forts and even go back weeks later (game time) and theres just a few bandits.

I don't know if it's happening to every fort, but I have seen about four or five forts which I have found and cleared from bandits or storm mages. This has happened several days after the civil war quests were over. In a few days the bandit bodies has been removed from fort and it's filled with Stormcloak soldiers. All forts I have seen this happen has had blacksmith forge and place for horses.

Fixed

I agree, I've actually cleared forts with the sole intent of having the empire occupy them. It adds a lot of realism to the game.