In Elie Wiesel's Night, the selection at Gleiwitz happens late in the book. The prisoners have been on a long, deadly forced march in freezing weather. Many died along the way. After reaching Gleiwitz, the Nazis conduct this selection to weed out the weakest of the survivors.
When Elie’s father is told to go to the left (the side for those “selected”), Elie runs to his side. This creates enough confusion for both of them to slip back over to the right (safe) side. This was done at great risk to his own safety, as this excerpt attests:
Several SS men rushed to find me, creating such confusion that a number of people were able to switch over the right—among them my father and I. Still, there were gunshots and some dead.
Wiesel does not say that he ran to his father’s side for the purpose of saving him. Throughout the story he has stressed the idea that he and his father have tried desperately to remain together. It may be that he ran to his father’s side simply to be with him, regardless of the consequences. Their escape to the right might have been a bit of luck, Wiesel doesn’t say.
Elie's devotion to his father will be tested later as his father weakens. This scene helps establish the contrast in Elie's behavior as concentration camp life wears down him down psychologically and emotionally.
Shortly afterwards, the survivors are loaded onto cattle cars. Of the approximately one-hundred prisoners in Elie’s car, only 12 (including Elie and his father) survive the brutal trip to Buchenwald.