World War II lasted from 1939 to 1945, although conflicts began earlier. It involved the majority of the then-world states – including the great powers (US, Soviet Union, England, France, Germany), eventually creating two rival military alliances: the Allied powers and the Axis powers.
The instability created in Europe after the First World War (1914-1918) has paved the way for another international conflict – the Second World War – which erupted two decades later and proved even more disastrous.
Adolf Hitler and the Nazi party took power in the then politically and economically unstable Germany and signed strategic treaties with Italy and Japan to advance their ambitions for world domination. Hitler’s invasion in Poland in September 1939 led Britain and France to declare war in Germany, and so the Second World War had begun.
The total number of people who lost their lives during the Second World War is shocking; it is estimated at 50 to 85 million losses. These data made World War II the most deadly conflict in human history. These include, among others, the Holocaust (in which more than 6 million Jews were killed in the Nazi concentration camps) and the bombing of industrial centers and residential areas.
The opposing forces were the Axis powers (Germany, Italy, Japan, etc.) and Allied powers (Soviet Union, USA, United Kingdom, France, China etc.), where the winners were eventually the Allied Powers.
The “innovation” of this war was the use of the atomic bomb by the United States (in Hiroshima and Nagasaki in Japan). Also, with the end of the war, the Cold War began, due to US-Soviet Union competition for world domination.