Some more thoughts I had.
If the players are involved with the war, how do their actions effect the outcome of it? There are simple answers, in a given battle, if they fight and do well that battle goes well, less cassulties on that side etc.
What if the players have to choose from multiple options. Go to this town and help hold the bridge there, or travel to that mountain pass and hold it. Sneak behind enemy lines and harass the enemies supply lines, capture a general from the other side and return him to our side.
If the war is dynamic, the situation should change regularly, each desision the players make leads to a new battle field with new tactical options, with new benifits and challenges from the last time they looked, so to speak.
An example: The players choose to help defend the town so to prevent civilian casulties, thus the mountain pass has been takin and reinforced with a hastiliy built fort, but the players managed to recruit more troops from the town they saved so they have a little more resources to work with. Having preserved the bridge gives the players the option of moving behind enemy lines, but they must move out quickly before the enemy closes the gap. The general that was moving forward with his troops because they were winning now feels unsafe and moves his command tent to a much more secure location.
The more I think about it, as the GM, you need to have a fairly complicated set of situations built to handle the first few desicion points the players make and still keep things moving. Making a flow chart seems like a reasonable idea for the war and the choices the players make.
-Scott**modified for sig