Ratzinger's family, especially his father, bitterly resented the Nazis, and his father's opposition to Nazism resulted in demotions and harassment of the family.

Following his 14th birthday in 1941, Ratzinger was conscripted into

the Hitler Youth—as membership was required by law for all

14-year-old German boys after March 1939—but was an

unenthusiastic member who refused to attend meetings, according to his brother.

​

 In 1941, one of Ratzinger's cousins, a 14-year-old boy with Down syndrome, was

taken away by the Nazi regime and murdered during the Action T4 campaign

of Nazi eugenics. In 1943, while still in seminary, he was drafted into the

German anti-aircraft corps as Luftwaffenhelfer.  Ratzinger then

trained in the German infantry.  As the Allied front drew closer

to his post in 1945, he deserted back to his family's home in

Traunstein after his unit had ceased to exist, just as

American troops established a headquarters in the

Ratzinger household. As a German soldier, he was 

interned in a prisoner of war camp, but released

a few months later at the end of the war in May 1945.