Memorial Day: America’s 7 costliest wars

2. World War II
World War II was the largest war in human history in terms of deaths, geographic scope and the number of nations involved. Its effects continue to shape the modern world.
The U.S. entered the conflict in December 1941 after Japan attacked Pearl Harbor and ultimately played a major role in the Allied victory in 1945.
According to the National World War II Museum, approximately 416,800 American service members were killed during the war, along with roughly 1,700 civilians.
The conflict also included two of the deadliest days in American history: the Dec. 7, 1941, attack on Pearl Harbor, which killed about 2,400 people, and the D-Day invasion of Normandy on June 6, 1944, which resulted in approximately 2,500 American deaths.




