We always hear about Kings and Dukes waging war and conquering lands in medieval history. We have Norman lords in England, Italy, Sicily and Antioch. Spanish knights in Spain during the Reconquista. And of course, the entire hundred years war. Often the conquering seems to have happened for no other reason than they could, which was especially true when facing enemies they considered pagans or infidels. But equally often they seemed to claim some sort of justification for their conquering. I’ve, for example, heard the battle of Agincourt be described as a legal argument for Henry V’s claim to the French throne.
But how did things work on the lower end of the scale of nobility.
That feuds and vendettas was common between individuals, families and similar groups is also well recounted, such as in the Scottish and Welsh border marches and the Italian city states, but did such local issues ever switch from vengeance and robbery to regular conquest of land?
At what level in the aristocracy could wars of conquest take place?
Could an ordinary enfeoffed knight expand his fief by taking over a neighbour's manor by force of arms? Could a baron or a count/earl? Or did it only happen under a campaign that was under the leadership of a head of state such as a king or duke? Was it allowed if they had some casus belli as justification such as a previous ownership claim?
How did the liege lord of the conquered fief react and what happened to possible vassals of the conquered fief?
I know that the vassals supposedly were meant to come to their liege lord’s defence but did they risk losing their lands along with their liege lord, even if they were inherited grants and their lands wasn’t actually invaded?
Guess what I’m trying to ask is during the middle ages did private wars (not part of a sanctioned national effort aka France vs. England) of conquest for land take place within a kingdom or between two different kingdoms and who waged them and how did it work legally within the confines of vassalage feudalism?
(I apologize for my rambling question. It is just that I was not sure how to phrase it in such way that made it clear that it wasn’t the wars of great lords that were the focus of the question nor actual tactics and warfare.)
Vassals not longer fighting themselves within the same kingdom is a result of many changes during the centuries, which came to be in the Early Modern Age. All wars before the 1600s I'd say, were private wars of a king against another king rather than between states.
War between two lords of any level - even two noblemen which weren't counts or dukes but simply had land and were aristocrats - most of times meant going on a small raid with a retinue of friends and relatives to take the livestock and wreck the fields, perhaps burning a few houses. It was on a very small scale but it was frequent.
If a lord wanted to take a possession from another lord, again, at any level, he was not bound by many laws to do that since it was a right to wage war in the ideological structure of society, especially if it was backed by an appropriately researched claim and since they had very large degrees of autonomy.
Reasons for war could have been things like refusing to lift taxes from travelling merchants passing through (a favorite of Italian city-states), or to settle a dispute over the ownership of that piece of land belonging to a person which lived on this side of river but died on the other side other can claiming ownership of that one castle.
Vassals not wanting to join the king's wars became increasingly common as time went on. They usually had some laws or customs which set the amount of time they were compelled to serve, varying based on the region. Around 1250 the owed military service had declined to the point that knights and lords were regularly recruited and employed through contracts and the kings accepted monetary compensations for not joining (scutagium). They would have their lands confiscated only if they were bound by an oath of vassalage and if they had commited a serious crime such as treason. In that case, they would be stripped of their possessions.
The defeated lord's liege might have complained to the winner's sovereign although, if the war was a regular one, little would be done. Perhaps a monetary compensation might have been proposed but I'm uncertain, it's just a hypothesis.
Sources:
Contamine, P., "War in the Middle Ages", Blackwell Pub, 1986;
Le Goff, J., "Time, Work and Culture in the Middle Ages", University of Chicago Press, 1980;
Vallerani, M., Provero, L., "Storia Medievale", Mondadori Education, 2016