The soldiers that died on the battlefield were usually collected and sent back to their home countries, regardless of whether they were their soldiers or the enemies. Their deaths would also be recorded in the military reports and sent back along with them.
They would transport the corpses belonging to the enemies to an open field where they would be burnt. On the other hand, their soldiers would receive a proper burial ceremony before they are cremated. Their ashes would then be collected and sent back to their own families.
It was said that this was a rule which had been decreed by The Lord to manage the corpses found on the battlefield and all kingdoms were expected to comply with this rule.
However, when the war got more intense, and over a thousand people had died on the battlefield, it required a lot of manpower to manage the corpses. Therefore, some kingdoms were lazy to retrieve all the corpses. It was unnoticeable if 30 or even 50 corpses were missing from the battlefie...