The United Kingdom and France subsequently declared war on Germany on 3 September. World WarВ II is generally considered to have begun on 1 September 1939, when Nazi Germany, under Adolf Hitler, invaded Poland.

The exact causes of World War II are debated, but contributing factors included the Second Italo-Ethiopian War, the Spanish Civil War, the Second Sino-Japanese War, the SovietвЂ“Japanese border conflicts, the rise of fascism in Europe and rising European tensions since World War I. In the wake of the Axis defeat, Germany and Japan were occupied, and war crimes tribunals were conducted against German and Japanese leaders. Tens of millions of people died due to genocides (including the Holocaust), starvation, massacres, and disease. World WarВ II was by far the deadliest conflict in human history it resulted in 70 to 85 million fatalities, a majority being civilians. Aircraft played a major role in the conflict, enabling the strategic bombing of population centres and the only two uses of nuclear weapons in war.

In a total war directly involving more than 100В million personnel from more than 30 countries, the major participants threw their entire economic, industrial, and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. It involved the vast majority of the world's countries-including all of the great powers-forming two opposing military alliances: the Allies and the Axis powers. World WarВ II or the Second World War, often abbreviated as WWII or WW2, was a global war that lasted from 1939 to 1945.

Civil war file cards for the letter d