What does Elie have to fight for when the train stopped in the middle of a deserted field?

Elie fights for his father. Eliezer's father is near him, but does not respond to his call and seems dead. When the train stops, SS officers order that corpses be thrown out of the car. Two men begin to throw Eliezer's father out of the train, but Eliezer revives him by slapping him viciously and screaming desperately in his face.