(CNN) -- Before he was Pope Benedict XVI, before he earned the nickname "Cardinal No" as the enforcer of church doctrine, he was Joseph Ratzinger -- the son of Maria and police officer Joseph Ratzinger, learning about life and God in Germany between two world wars. 

According to Roman Catholic doctrine, Benedict is not only the church's leader but God's representative on earth and infallible. 

He is also a man -- one who savors his meat and potatoes, an accomplished pianist who loves Mozart, and a teacher who for years commanded university classes. His humanity became apparent Monday, when the Vatican announced he'd resign at month's end "because of advanced age," becoming the first pope in nearly 600 years to do so. 

After his birth on April 16, 1927, in Marktl am Inn, in southeastern Germany near the Austrian border, Ratzinger's early years were defined by his country and the turbulent times, as well as his faith. 

Adolf Hitler rose to power during Ratzinger's adolescent years in Traunstein, in the heavily Catholic region of Bavaria. When he was 14, school officials followed Nazi officials' orders and enrolled him and the rest of his class in the Hitler Youth movement -- against his will, Ratzinger wrote in his memoir. 

He left the organization shortly thereafter, because he was studying for the priesthood. But in 1943, Ratzinger was brought back into the Nazi fold upon being drafted into the German army. 

For the next two years, Ratzinger served his country as part of an anti-aircraft unit. But in the waning days of World War II, he deserted -- and was taken prisoner by the U.S. Army. 
When exactly was he born?
on April 16, 1927