Yes, it happened. It was not ordinary, and only under extenuating circumstances became the go-to strategy for typical medieval warfare. This may not seem like the huge distinction some of you are looking for, but it is a distinction.
William the Conquerer is one of the few examples of a noble from culture A sailing over and completely conquering a large piece of land from culture B whereupon he and his vassals and descendants held it for more than a little while. One of the characteristics of this conflict that distinguished it from a lot of medieval warfare is that he was totally uninterested in ruling the people who lived in the Saxon-held North -- some of them, anyway, since he did end up assimilating a significant number despite the harrying.
The other big example of this kind of thing was in the Hundred Years' War, when it was called
Chevauchée. Two key features:
- Both the French and the English shifted to it because of the Black Death: neither side had the manpower for protracted siege warfare any longer. The English also didn't have the best leadership after Edward III until Henry V came around.
- Although a lot of damage was done, it also just didn't really work. It caused a lot of misery but it didn't result in lots of land changing hands, because it diverges from BM in that pillaged regions wouldn't 'go rogue' - if you couldn't occupy and hold an area, it might produce a crap harvest for a year, but it still belonged to whomever it had belonged to before after that.
The period between the death of Edward III and Henry V was the high point for this kind of thing and the low point for actual progress in the war (on either side). Henry V turned things around and stopped doing it as much (the famous 'when thou art King, do not hang a thief' bit) and his were the last great gains made by the English during the war.
This may seem like an academic distinction and it certainly isn't a complaint. The way BM is right now, the system more or less makes sense. It sounds like the devs are already working on some good long-term solutions. The only other suggestion I'd make is to further reduce the influence of peasants on who holds regions: peasants kicking out lords is still way too common in BM, or at the very least, it happens for the wrong reasons. But that leads to a larger discussion: medieval warfare did not feature 'takeovers' at all, but sieges and occupying castles. If you held the castle, you held the region. The business of 'convincing the populace' or replacing the bureaucrats is a BM invention, at least until you start getting into the Renaissance and more urban warfare with cannon - at which point 'conquering a city' did require that you consider the burghers and bureaucrats more because the burghers and bureaucrats controlled a lot more of the purse strings.
