For this kind of game, the Civil War battles are pretty good. Definitely one of the most impressive things about Skyrim, considering how piss-poor battles were in Oblivion.
Well in Oblivion, you could have multiple followers, and I found myself a rather large and entertaining skirmish I'm sure you will enjoy.
First, build your squad. Finish some questlines and get a few add-ons and you should have access to maybe about a dozen followers. Have them all follow you to Fort Sutch from the Dark Brotherhood questline.
When you get to the point in the main questline when Oblivion gates open up everywhere, go to Fort Sutch. You will meet four or five Imperial Guards who will ask you to drive off some Daedra. Accept and then enjoy the carnage as two large forces smash together in the fields of County Anvil!