There are occasionally wars in-game, although the action takes place off-screen. Your character will have the option to join the war after going to your town's armory. If your side wins the war and you participated in it, you will be eligible for a share of the bounty. If your side loses the war, you may be required to pay reparations. Be cautious when deciding to send a character to war, since there is a possibility of dying.
If your side wins the war and your character survives, you will gain imperial fame which will is a requirement for certain government positions.