Why Do Wiesel And His Father Leave Buna?

Night is a memoir written by Holocaust survivor Elie Wiesel. In the book, Elie and his family are sent from their hometown of Sighet, Transylvania to Auschwitz. From there, they were sent to a different camp, Buna.
Wiesel and his father decide to leave Buna as they think they will have a better chance to survive if they evacuate the camp with the prisoners and Germans. They also hear the rumors that everyone in the hospital will die.
Because the Russians are advancing, the Germans want to evacuate Buna and move to another concentration camp. All prisoners are forced to go with them, but those in the infirmary are allowed to stay behind. Wiesel was just recovering from foot surgery and could have stayed behind in the infirmary, but he and his father think those who stay behind might be exterminated.
SS officers then force the prisoners to run through the snow to Gleiwitz. Finally, in Chapter 7 of Night by Elie Wiesel, Elie and his father are two remaining survivors out of 100 from Buna. They endure harsh elements and bitter cold as they travel for ten days to another concentration camp in Buchenwald.