In his article “The East is Ablaze: 1919-1926” Chris Peers outlined a simple but effective method for running a campaign without a map, and ignoring all those pesky things that can bog a campaign down (politics, diplomacy, economics and logistics).
I am a fan of campaigns and I’ve tried a few things involving the DBx family of tactical rules. The campaign system included in DBA/HOTT is ideal for one day events. And the same DBA/HOTT campaign system can be tweaked to make campaigns with more detailed tactical rules; I’ve run a couple of big DBM campaigns like this. But over time I have returned to the basics and used DBA/HOTT for the tactical rules as well. My latest initiative like this was Britannia 600 AD. DBA/HOTT are also a good complement for campaigns using Engle Matrix Games.
The essence of Engle Matrix Games is that they allow you to do whatever you want to, so long as you can make a logical argument. You play a leading general of the period. Each turn you get to make one argument/order about what you want to happen that turn. You can make arguments for your side, to cause problems for the other side, or to change the rules! (No more than one level of rule change.)
This is a list of the campaign rules (and one day multi-player games) scattered around my site.