You really should look at the campaign system in “The Sharp End” by TooFatLardies. It is very flexible, can be any length of time, any area and can be map driven. It is for Chain of Command, a platoon-level game, but it really isn’t bounded by that. It does include following characters, medals, etc. and you can add all the details, chance events and such that you want. It has been fun customizing it to the Spanish Civil War.