Originally Posted by Doppleganger

It has to be the German victories of 1939-42. Note I say German because it would be unfair to Germany to give any of the other Axis partners joint credit.

Why?

Well because it changed the face of warfare forever. Now, for the first time since the Mongol armies thundered across the plains of Asia 800 years ago we had an army that began to move faster than the speed of the marching man. Anyone who's ever read 'Panzer Leader' by Heinz Guderian will realise what a struggle it was for the German Panzer arm to get started. Without Hitler's favour and Guderian's brilliance and perseverance against the odds the Germans would have lost the initial Battle of France and a new dawn of trench warfare would have set in. But it didn't. Instead, Germany's armies with Panzers at their spearheads crushed every army in their path in the first three years of war. The great Allied victories in Europe took their cue from those first three years and all modern armies today take their cue from Blitzkrieg.