Ah, the “Nazi Pope” threw us off.
Yes, as a youth Josef Ratzinger was compelled to enter the Hitler youth and later the military. He later deserted before the war ended. From Wikipedia (consistent with the facts that came out when this whole question came up):
“Following his fourteenth birthday in 1941, Ratzinger was enrolled in the Hitler Youth — membership being legally required after December 1939 — but was an unenthusiastic member and refused to attend meetings. His father was a bitter enemy of Nazism, believing it conflicted with the Catholic faith. In 1941, one of Ratzinger’s cousins, a 14-year-old boy with Down syndrome, was killed by the Nazi regime in its campaign of eugenics. In 1943 while still in seminary, he was drafted at age 16 into the German anti-aircraft corps. Ratzinger then trained in the German infantry, but a subsequent illness precluded him from the usual rigours of military duty. 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 their headquarters in the Ratzinger household. As a German soldier, he was put in a POW camp but was released a few months later at the end of the War in summer 1945. He reentered the seminary, along with his brother Georg, in November of that year.”