Answer:
World War II was the biggest and deadliest war in history, involving more than 30 countries. Sparked by the 1939 Nazi invasion of Poland, the war dragged on for six bloody years until the Allies defeated Nazi Germany and Japan in 1945
WW2 was also deadly because Soldiers died from simple combat in charging from the trenches and from bombings in the trenches and snipers and such. Disease was also a major factor in deaths, and the Spanish Flu killed a LOT of soldiers and civilians.