World War II was the largest and most destructive war in history. Some 100 million people fought as combatants across Europe, Africa, and West and East Asia. This series describes why and how the war was fought, and explains its impact on those who lived through it. World War II was not only fought on the battlefield. Naval forces struggled to keep the Atlantic sea lanes open, while bombers reduced enemy cities to rubble. Scientists developed new technology and mathematicians broke enemy codes. This book explains how activity away from the actual fighting helped the Allies to win the war.