At first, Wiesel did not react in any way when a Gypsy slapped his father. The brutal living conditions and starvation made the prisoners scared of any actions against the Nazis. Later, Eliezer felt very guilty.
Detailed answer:
Night is the first part of the trilogy titled Night, Dawn, Day by a Romanian-born Jewish writer Elie Wiesel. In 1960, Hill & Wang published the memoir. It contained the author’s narrative of the gruesome events he experienced during the Holocaust. When Wiesel was a 15-years-old boy, he had to enter a cattle wagon with his father and move to Auschwitz. The Nazis wanted to humiliate the Jewish captives, so they shaved Weasel’s head and replaced his name with a number.
The inhumane conditions of the camp made its prisoners doubt or reject the Jewish identity. Yet, Elie decided to preserve it. In Night, Wiesel described his fight for life in the camps. He admitted that starvation determined his existence and made him more reserved and patient. Under stress, some prisoners expressed anger and atrocious behavior. However, survival instincts prevented the captives from any rebellions and arguments with the officers.
The Nazis selected some prisoners to control the inmates and gave them the power to punish the offenders. When a Gypsy assisting the guards slapped Elie’s father, the boy did not do anything. He was scared of the violent Gypsy and the German officers. So, he helplessly watched his father lying on the floor in pain. The older Wiesel appeared unstirred. He taught his son the lesson on preserving dignity despite the loss of humanity around them.