The only thing I can think of is America's defenses were depleted by a rival civilization and the natives took them over before they could rebuild their defenses.
Thats true. I've once seen a french city defended only by an axeman.

The only thing I can think of is America's defenses were depleted by a rival civilization and the natives took them over before they could rebuild their defenses.
The only thing I can think of is America's defenses were depleted by a rival civilization
@ Black Whole: And you say even more collapsed! I wonder what caused this.
@ Black Whole: And you say even more collapsed! I wonder what caused this.
How did you lower the penalty for overexpansion? What did you need to edit?
elif (iBuilding == con.iCourthouse or iBuilding == con.iAztecSacrificialAltar or iBuilding == con.iSumerianZiggurat): #courthouse
if (not city.hasBuilding(con.iPalace) and not city.hasBuilding(con.iForbiddenPalace) and not city.hasBuilding(con.iSummerPalace)):
if (self.getStability(iPlayer) < 0):
self.setStability(iPlayer, self.getStability(iPlayer) + 1 )
if (iPlayer == con.iTurkey or iPlayer == con.iAmerica or iPlayer == con.iPortugal or iPlayer == con.iNetherlands): #they have too much foreign culture
if (iPlayer == con.iTurkey or iPlayer == con.iAmerica or iPlayer == con.iPortugal or iPlayer == con.iNetherlands or iPlayer == con.iGermany): #they have too much foreign culture
This is so typical!I noticed, that the remaining civs seemed to think "Oh! Independents = Free territory for everyone!". IMO, they captured city after city, which made them collapse.
In the past I did something similar.And that's why I lessened the penalty for overexpanding. I hated that every time you have a strong AI it collapsed due to overexpansion.
once you conquer entirely an other civ, then that civ is dead...Is there a way to make it so that the owning someone else's home turf penalty only applies if that civ is still alive? That way An empire expanding to take over little duchies won't suffer the instability that they would if they attacked a full-fledged nation.
Wow, I've never seen that many independent cities before! I can not imagine how it happened. That is definitely an OMG Moment.
Just happened... in 1778, but I think it's a bug :
America owned by natives ! Incredible ! (and a nederland town near seattle).