A prisoner exchange or prisoner swap is a deal between opposing sides in a conflict to release prisoners: prisoners of war, spies, hostages, etc. Sometimes, dead bodies are involved in an exchange.[1]
Geneva Conventions
Under the Geneva Conventions, prisoners who cannot contribute to the war effort because of illness or disability are entitled to be repatriated to their home country. That is regardless of number of prisoners so affected; the detaining power cannot refuse a genuine request.[2]
The Second World War in Yugoslavia saw a brutal struggle between the armed forces of the Third Reich and the communist-led Partisans. Despite that, the two sides negotiated prisoner exchanges virtually from the beginning of the war. Under extraordinary circumstances, these early contacts evolved into a formal exchange agreement, centered on the creation of a neutral zone, possibly the only such in occupied Europe, where prisoners were regularly swapped until late April 1945, saving several thousand lives.[4]
^Gaj Trifković, "Making Deals with the Enemy: Partisan-German Contacts and Prisoner Exchanges in Yugoslavia, 1941–1945" in: Global War Studies 01/2013; 10(2):6–37.