World War II (1941–1945) | Causes, Major Battles, and Historical Timeline Explained World War II (1939–1945) was the deadliest and most significant global conflict in human history, involving over 100 million people across more than 30 countries. This video focuses on the crucial years 1941 to 1945, highlighting the turning points, major battles, and ultimate outcomes that shaped the modern world. From the German invasion of the Soviet Union to the D-Day landings, the Pacific battles, and the fa