In my current game as Aquitaine, poland got completely taken over by the swiss band right near the start, since then the duke level mercenary captain has remained completely static for 50 years except for some mild rebellions. Most his vassals are german now. I've seen very brief mercenary states before (e.g. bulgarian band in north africa, saxons in the papal states) but i never see them lasting long. Am i right in thinking that since they are open elective and thus have no claims through marriage or inheritance, no de jure territory and no special CB like republics that they are pretty much the most peaceful neighbors possible? Do they even join crusades? I've never seen the captain even create another duke title, he just holds a varying amount of counties.
On another note, whats the most successful mercenary state you've seen?
On another note, whats the most successful mercenary state you've seen?