In vanilla MTW2, cities could upkeep for free any non-artillery unit they are capable of recruiting, in SSHIP both cities and castles have free upkeep slots, but I started a new game as Poland it seems that they are only capable of free upkeep for Eastern Slavic Militia(both cities and castles), even though they have the capacity to recruit more types of units. Even for "Local Militia" class units like Woodsmen, the free upkeep does not work. Anyone know what is the mechanic behind that? How does a specific type of a unit become eligible for being free upkeep? Is this described anywhere?