Almost since the advent of warfare, civilians have suffered ‘collateral damage’, but the concept of Total War – a war without limits – only surfaced in the early part of the twentieth century. The idea of huge numbers of aircraft raining death upon defenceless cities was seen by many as not only barbaric but, in practical terms, quite unrealistic given the logistical challenges that would have to be overcome in order to put them into practice. Any complacency over the threat, however, was rudely shattered on 26 February 1935, when Adolf Hitler officially signed a decree authorizing the formation of the Luftwaffe. The third branch of Germany’s armed forces erupted on to the European military landscape. Its blustering claims of irrepressible air power sent waves of panic rippling through ministries of war throughout the world. Framing a realistic response to Hitler’s propaganda offensive proved to be problematic given the lack of detailed knowledge of not only the numbers, but also the true performance capabilities of his new generation of aircraft and the ways in which they had expanded the boundaries of war. It was, therefore, of huge interest to all modern military establishments when these machines were deployed during the Spanish Civil War which broke out in July 1936. Notwithstanding the limited scope of this conflict, it offered, for the participating nations, a testing ground for new machines and, for the interested observers, a window into the future of aerial warfare. When the Spanish Civil War was less than a year old it had already seen air power employed in most of the ways that it would be used in the Second World War. This not only included airlifting troops, reconnaissance, interdiction, close support and strategic bombing, but also the deliberate targeting of civilians as a means of achieving military objectives. This book looks at all the significant aerial engagements of the war and examines them against the background of the wider global context. In this way, the Spanish Civil War’s part in the evolution of air power is confirmed, as is the way in which its lessons were learned, or ignored, in the context of the much greater conflagration that was to come.