In M2TW Kingdoms; Crussader, any FMs can build stone forts, and in Brittania, the stone forts are permanent... I'm just curious, if the Roman / Greek forts are upgradeable (initially wood, but can be upgraded into permanent stone fort) in EB II can recruit and retrain mercs / low levy units. So everyone can get reinforcements and retaining when they play a far flung campaign in enemy territory... I think its a good idea...