After you discover guerilla warfare, the Partisan unit becomes available. If you get a city taken over after this point (by barbs, AI, or whomever), you will see a message like "Citizens of XXX city take to the hills!" or something. And then the city you just lost is literally surrounded by these NONE partisan units before you begin your next turn. The units are now yours, but the city is no longer yours. You can probably take the city back at your leisure, but the bonus is you get around a dozen NONE partisan units under your control.
If you've never had a city taken away from you late in the game (after you've discovered guerrilla warfare), you probably have no idea what I'm talking about. Give it a try.
If you've never had a city taken away from you late in the game (after you've discovered guerrilla warfare), you probably have no idea what I'm talking about. Give it a try.
Comment