Why do Wiesel and his father leave Buna? How do they respond to the circumstances of the forced march?

Eliezer and his father had the choice to leave Buna or stay put. It is a painful irony that Eliezer and his father decided to be evacuated from Buna with the rest of the prisoners. They think they will have better conditions there, but Buna is liberated before them. The forced march is hell through the cold. The SS officers make the prisoners run through the snow, and they shoot those who fall behind. Eliezer feels separate from his body and wishes he could get rid of it because it is too heavy to drag along. He begins to run mechanically and starts to lose his sense of self. A man named Zalman suddenly gets a stomach cramp and has to go to the bathroom; he falls and is trampled by the crowd. Eliezer wants to die to stop feeling the pain, but knows that he must keep going in order to help his father.