Beware who comes here, for English is not my first language.
I was reading a post here about late medieval Europe and while I'm familiar with the fact that highborn enemies could be captured for ransom rather than killed, I wonder how did that actually work. In the aforementioned post, a contributor states that
If soldiers were able to identify a particularly important individual, there would probably have been a mad scramble to capture him rather than kill him outright, both for political purposes and for the potential for ransom profits. This happened to the French king Jean II at Poitiers, who was taken prisoner in a furious melee where other high-ranking French aristocrats, who ordinarily would have made excellent ransoms, were killed (possibly by accident as English troops swarmed to grab Jean specifically)
It seems there was competition to be the one to capture an important enemy. How were those claims disputed in the middle of a battle? Were there any 'claiming rights', or were they shared among different individuals?
Another post tackled this issue slightly different. How did the 'capturing' work in the middle of a battle, or was it done after the whole thing?
Hello there !
I'll try to answer as best as I can and avoid to shoot off target.
As for the claims being disputed in the middle of a battle, it could very well happen. I can remember being taught about it, although I can unfortunately not remember who was at stake here, or who was fighting for him. Therefore, I'll not say much more on this subject to avoid saying mistakes and confusing you.
What I can develop, though, are the questions of sharing ransoms and of how the "capturing" would work.
Basically, the key word is "surrender". A man would become a prisoner from the moment he surrendered himself to his enemy. He would generally stop fighting and ask for mercy, eventually surrendering his sword to his enemy. A knight that would not stop fighting and ask for mercy would eventually be killed rather than taken captive.
An important point, though, was that a knight would surrender to somebody. Somebody in particular. That prevented a lot of infighting about who was the captor (that may answer a bit your first question, too).
An important side note is that you had to be noble and you had to be recognized as such to be spared and ransomed. Commoners were of low value. That has lead to dramatic errors at times, most famously at the Battle of Agincourt.
This battle is great for discussing captors and ransoming because of the tragic events that took place. In the middle of the battle, while the English had already captured a great deal of French knights, some French, going through woods, looted the English camp. Henry V, thinking himself surrounded, ordered the prisoners to be slaughtered so that they would not be freed by this new force and thrown into battle again.
Now I recall two different stories about one particular French knight and, as I am not currently home, I cannot check which one is the correct one. I'd be happy to correct this when I'm home if you need. The knight was the Count of Nevers, cousin to John the Fearless, Duke of Burgundy. he was therefore a relatively important noble and specifically the cousin of a "top 3" French noble. A great prize, then. Unfortunately, he arrived on the battle too late : fights had already started. Without taking the time to put his armor and coat of arms on, he grabbed his banner, used it as a tabard or coat of arms makeshift and rode into battle. Now i can't recall if he was brought down his horse and massacred by soldiers that did not recognize him as a knight or if he was a victim of Henry V orders (Henry having ordered to spare the most prominent nobles only), not being recognized for who he was for his lack of armor, proper coat of arms etc.
Finally, even if it was expected for the captor to grant mercy to an opposing knight, that was not mandatory. By surrendering, one would place his life in the hands of his captor, for him to do as he pleases. Being a prisoner did not mean being spared at any rate. It was totally expected, though, and Henry V's actions were heavily disregarded among French nobility. It was considered barbaric of him.
I mentioned in another thread (https://www.reddit.com/r/AskHistorians/comments/defaaj/in_medieval_europe_did_the_average_peasant_care/f2vfxro/?context=3), a commoner would not really be able to ransom a knight he captured. He would have lacked the contacts or means to contact his prisoner's family to demand a ransom, he would have lacked the "facility" to keep his prisoner, feed him, ... Therefore, most knights captured by commoners were, in fact, "bought" to their captor by the liege of said captor. Sometimes, such a system would repeat, generally if the prisoner was considered of utmost importance or rank. Joan of Arc, for instance, was brought down her horse by a Burgundian commoner, surrendered to a Burgundian knight (here you see the importance of surrendering to someone), was sold to Jean de Luxembourg, a high ranking Burgundian noble and then sold to Philipp the Good, duke of Burgundy, who himself sold here to the English.
This system was considered totally normal, and lieges would even often take a portion of their vassals prizes (between a quarter and a third, in general).
The captured knight would give up his sword and his other weapons and would be held captive with other nobles in the back of the battlefield, generally speaking. He would be watched by some men, too.
Escaping after being captured, though, was considered dishonorable (pretty much the opposite of, say, the world wars). You pledged not to try and run. Also, nobility was not so big at the time, and it could be known rather quickly that you escaped once in your past, making it quite difficult for you to convince someone that you would not try again, were you be captured once more. It would have been a dangerous game. It could happen, nevertheless.
An example I can give you on the subject was Jean le Bon, king of France. Being captured, he was authorized to go free after paying a part of his ransom, promising to pay what remained and providing some hostages. Later on, the hostages escaped while they had been authorized to meet their wives in Calais (and were not at this time monitored, for obvious reasons). Jean, threatened with war by the English and considering that his honor has been soiled as his word had been broken, went back in captivity "willingly" (and was kept in rather harsher conditions).
I hope that helped ! As I said I was not home while writing all that, and therefore I'll be ready for follow-up questions and clarifications.