What Was WW2?

WW2 Intro Photo (Pearl Harbor) World War II was a collection of many regional conflicts that all interacted with each other, strategically and politically. The separate wars that made up WW2 were as follows:

The European War

The European War included Germany's two fronts, one against the Western Allies and the other against the Soviet Union. To the north, Finland and Russia fought two smaller wars that influenced the outcome of the European War as well. Notable events of this war included the Battle of Stalingrad and the Normandy invasion.
The Pacific War

The Pacific War was primarily fought between Japan and the United States. Notable events of this war included the Attack on Pearl Harbor, the Battle of Midway, and the Battle of Iwo Jima.
The Second Sino-Japanese War

The Second Sino-Japanese War was the first war to begin; this war was later encompassed into the China-Burma-India Theater in the overall Allied war plan. Notable events of this war included the Second Battle of Shanghai and the Rape of Nanjing.
The Desert War

The Desert War was a war fought to secure the soft underbelly of Europe.
The Atlantic War

The Atlantic War had critical consequence for the United Kingdom as she relied so much upon the sea to survive.
There were also other minor conflicts that influenced WW2, such as the Italian invasion of Abyssinia, the Spanish Civil War, and the Soviet-Japanese Border Wars.