Melee (from the French mêlée IPA: [mɛle]) generally refers to disorganized close combat involving a group of fighters. A melee ensues when groups become locked together in combat with no regard to group tactics or fighting as an organized unit; each participant fights as an individual.
During the Middle Ages, tournaments often contained a mêlée consisting of knights fighting one another on foot or while mounted, either divided into two sides or fighting as a free-for-all. The object was to capture opposing knights so that they could be ransomed, and this could be a very profitable business for such skilled knights as William Marshal. There was a tournament ground covering several square miles in northern France to which knights came from all over Europe to prove themselves in quite real combat. This was, in fact, the original form of tournaments and the most popular between the twelfth and thirteenth centuries—jousting being a later development, and one that did not completely displace the mêlée until many more centuries had passed. The original melee was engaged with normal weapons and fraught with as much danger as a normal battle. Rules slowly tempered the danger, but at all times the melee was more dangerous than the joust.
BTW, In 1130 Pope Innocent II at the Council of Clermont banned tournaments and denied Christian burial to those killed in them.