False narrative! Nazi-regime did not put some people in gas chambers, they exterminated millions of Jewish men, women, children, and babies. The Nazi-regime also got 50 million white Christians killed in WWII Europe.
Before the US entered the war in Europe after the Japanese bombed Pearl Harbor, the Japanese Empire had murdered 5 million civilians in China, Manchuria, Indo-China, Philippines, Indonesia, Burma.
Hittler committed the biggest military blunder in military history by sending his troops into Russia with a no retreat order in the winter. The number of German soldiers who died in Russia during World War II is estimated to be between 5 and 7 million and an estimated 20 million Russians died. This makes the Eastern Front the deadliest theater of war in human history. — Then your hero shot himself in the head.