What was the worst thing happened in WWII?

Question:

What was the worst thing happened in WWII?

In Asia and Europe

Best Answer - Chosen by Asker: It's hard to know what qualifies as a "thing."

We're all familiar with the deaths of about 10 million Jews, socialists, homosexuals, Gypsies and mentally retarded children at the hands of the Nazis. Is that one thing?

The invasion of the USSR was horrible. The Soviets lost about 20 million civilians in the war.

The 15 years of Japanese predation in China cost about 40 million Chinese their lives, and launched the arguably disastrous career of Chairman Mao.

Of these "things," you might by counting argue that the last was the worst.

I'm especially horrified by elements of each of these, especially horrified by the Nazi "Aktion T4," which predated much of the rest of Nazi atrocities, and focused on "purification" of the "Aryan race" by exterminating children with perceived deficits.

The Japanese Imperial Army's focus on rape and on killing children as tactics of war stands out for special mention as well.