Authors:

I think in many ways, the Spanish Civil War was the first battle of World War II. After all, where else in the world at this point did you have Americans in uniform who were being bombed by Nazi planes four years before the U.S. entered World War II? Hitler and Mussolini jumped in on the side of Francisco Franco and his Spanish nationalists, sent them vast amounts of military aid, airplanes, tanks - and Mussolini sent 80,000 ground troops as well - because they wanted a sympathetic ally in power. So I think it really was the opening act of World War II.

Source: www.npr.org
I think in many ways, the Spanish Civil War was the first battle of World War II. After all, where else in the world at this point did you have Americans in uniform who were being bombed by Nazi planes four years before