Air strike on the road Barcelona - Tarragona (Robert Cappa photo)
German involvement began days after fighting broke out in July 1936. Adolf Hitler quickly sent in powerful air and armored units to assist the Nationalists. The war provided combat experience with the latest technology for the German military. However, the intervention also posed the risk of escalating into a world war for which Hitler was not ready. He therefore limited his aid, and instead encouraged Benito Mussolini to send in large Italian units.