At the end of the Second World War, millions of people are on the move in Europe.
As well as the large numbers of prisoners of war, homeless, refugees and former concentration camps inmates, large numbers of forced labourers join them.
One of the major concerns to the Allies was to register this enormous number of people and try to return them as quickly as possible to their home country. During registration, these people became known as "Displaced Persons" or "DP".
Maximum logistical effort was needed for this registration, administration and repatriation.
The railway system was virtually non-existent by the end of the war, as a result of bombardment and the fighting.
Many forced labourers were physically in an appalling state. Therefore, many hospitals had to continue to work or were newly created.
In order to avoid epidemics, all former camp inmates were deloused with DDT.
"Displaced Persons" originally from the west went home first. When they returned to their home country they faced yet another problem: many had to "prove" they had been used as forced labour, which was not always a straightforward task.
Those sent back to the east, had an even bigger problem: Stalin defined them as "Traitors". Many of them were arrested by the NKWD (the Soviet secret service) and transported to the Gulags further east and only were set free many years later.