World War II (WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945. It involved the vast majority of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis. It was the most widespread war in history, with more than 100 million people serving in military units from over 30 different countries.
Casualties for Allies:
| Great Britain + Commonwealth | 452,000 |
| France | 250,000 |
| USA | 295,000 |
| USSR | 13,600,000 |
| Belgium | 10,000 |
| Holland | 10,000 |
| Norway | 10,000 |
| Poland | 120,000 |
| Greece | 20,000 |
| Yugoslavia | 300,000 |
| Czechoslovakia | 20,000 |
| China (from 1937 on) | 3,500,000 |
| Total | 18,587,000 |
Casualties for Axis:
| Germany | 3,250,000 |
| Austria | 230,000 |
| Italy | 330,000 |
| Rumania | 200,000 |
| Hungary | 120,000 |
| Bulgaria | 10,000 |
| Finland | 90,000 |
| Japan | 1,700,000 |
| Total | 5,930,000 |