The German military’s rapid territorial gains in the early stages of World War II are often attributed to the tactical methods that later became known as ‘Blitzkrieg’ or ‘lightning war’. German forces assisting Franco’s Nationalist forces in the Spanish Civil War had been able to test the Blitzkrieg strategy. Combining powerful land and air action, the attacking force is spearheaded by armoured and mechanized or motorized infantry, with air support breaking through the opponent’s defensive lines, bombing key targets and establishing local air authority. Slower defending units become forced into pockets that can then be encircled and destroyed by armoured units. The speed and surprise of a blitzkrieg attack disorientates the enemy, ensuring that they are unable to form a coherent offensive, simultaneously destroying their infrastructure and communications. The Luftwaffe also used loud sirens, increasing the disorientation and psychological shock of their opponents. During the invasion of both Poland and France, the local terrain favoured the German attack style.
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