I don't remember exactly how the old strat system worked and Iv'e only waded through half the pages in this thread so this may have been mentioned or tried before.
If the main motivation for capture is to win the war, another one is to slap each other on the back after seeing "Rooks captured field A21."
So change it to a capture the sector game rather than capture the base.
In a given sector, you have bases, factories, and cities.
The bases have to be taken and the strats have to be taken down to a percentage, before you get the announcement "Rooks have captured sector 12"
Surely there is a finite size of a horde that can be mustered up. So they have to spread out over a larger area and have to defend their newly won bases, while trying to get control of the rest of the sector.