Military action.
The Soviet Union has most killed.
Germany
most likely the Jews...6-7million died
The Nazi Germans.
7 million Ukrainians were killed by Stalin during World War 2.
According to wikipedia it was World War 2 with 70 million people killed, most of whom were civilians. http://en.wikipedia.org/wiki/World_War_II
About 416,800 U.S. soldiers died in World War 2.
Simo Häyhä, had a record high 505 confirmed kills in world war 2. he was nicknamed The White Death
11,900 New Zeland Soldiers were killed during World War 2.
5.53 Million German Soldiers were reportedly to be killed during World War 2.
World War II had an incredibly larger number of deaths if including both civilian and military loss of life. In the second World War, over 60 million people were killed, and in the first World War, approximately 37 million people were killed.