Roland Johansen
Deity
I'm wondering if I should have just declared on her right after I wiped out Mansa. Is there a time period for the "we long to return to our homeland" complaint and/or the "War, unh, what is it good for?" to wear off??? Mansa's former cities were REALLY unhappy!!
The 'War, unh, what is it good for' is war weariness unhappiness. It is zero as long as you're not at war with the civilisation that caused the war weariness. If you redeclare the war after a short peace period, the war weariness will return at almost full strength. You will have to remain at peace for many dozens of turns before you can redeclare war with only a small remainder of the war weariness unhappiness.
The 'We long to return to our homeland' unhappiness is caused by the fact that a large fraction of the culture of the city is a foreign culture. You can see this by entering the city and looking at the culture bar in the city.
By producing culture in the city, the fraction of culture that is form your civilisation will increase slowly. So you should build some culture producing buildings in the city. It will take a long time to get a decent fraction of the culture in the core cities of the enemy civilisation that you've captured.
If you completely destroy another civilisation, then their culture will disappear and this type of unhappiness will disappear.
In the game described above, A couple of my older cities have a problem. One of them has decreased to size '1'. Other nearby cities have stabilized in the low-to-mid teens and one at around 21 or so. This one now at size '1' is surrounded by a fair number of cottages and a few farms.
Why does that happen? What can I do to get it to build again?
It could be that you're suffering from a lot of unhappiness from war weariness or you don't have enough food in these cities. I don't know what is causing it without seeing a savegame.