So far as I'm aware, Civ II is the only entry in the series to have had partisans which could spawn around a city when it was captured by an enemy. IIRC, this only happened late in the game (modern era) and they were generally no match for any other unit of the time, much less the endless waves of howitzers you would use to conquer the entire world with.
It's no surprise Firaxis tried different things instead in future Civ games, like trying to eliminate the 'One Unit To Rule Them All' issue, adding culture-flips (I remember people got upset about this showing up with Civ 3), making corruption and happiness a pain in the ass - to the point where you have a hard time conquering everyone and taking all their cities in Civ V with G&K and BTW, and an even harder time without G&K and BTW, largely because of the entire-civ unrest and permanent unhappiness for conquered or puppeted cities. In Civ II and SMAC there's little to stop you from rolling over the entire world if you have the superior military: corruption from distance largely only impacts per-city production, happiness is also per-city, and any unrest from taking a city is temporary and for that city only.
In Civ IV you could conquer another civ near the beginning of the game while everyone had warriors simply by pumping out as many warriors as possible and as much gold as possible and hitting their cities with all your warriors until their defenders fell. Of course, you had to do it before you ran out of money (due to having more warriors than you could afford upkeep for, because you needed 3 times as many warriors as your enemy had to pull this off, and it was pointless if they had better defenders). In Civ V the cities automagically regenerate health and get stronger, even under attack, and you don't want someone else's city at the beginning of the game anyways, all it would do is give you unhappiness.