I have noticed that my vassals have large reserves of levies I cannot call upon, and they can call each other to arms for internal conflicts. Some of them are listed as my "allies".
Can I call a vassal to arms, to raise the rest of his levy? It seems silly that peasant's up rise in their demise and they don't do anything unless I raise their levies.
Also, I'm crusading, and would like some of them to join in. Is it possible?