Blitzkrieg* (German for "lightning war") was an operational-level military doctrine which employed mobile forces attacking with speed and surprise to prevent an enemy from organizing a coherent defense. Originally conceived in the years after the First World War, it was a new tactic developing from existing techniques of maneuver warfare and combined arms warfare. It was first used by the German Wehrmacht during the Second World War. Strategically, the ideal was to swiftly effect an adversary's collapse through a short campaign fought by a small, professional army. Operationally, its goal was to use indirect means such as mobility and shock to render an adversary's plans irrelevant or impractical. To do this, self-propelled formations of tanks; motorised infantry, engineers, artillery; and ground-attack aircraft operated as a combined-arms team. Historians have termed it a period form of the longstanding German principle of Bewegungskrieg, or movement war. Methods of blitzkrieg operations centered on using maneuver rather than attrition to defeat an opponent. The blizkrieg thus first and foremost required a concentration of armored assets at a focal point, closely supported by mobile infantry, artillery and close air support assets. This required the development of specialised support vehicles, new methods of communication, new tactics, and the presence of a decentralized command structure. Broadly speaking, blitzkrieg operations required the development of mechanised infantry, artillery and engineering assets that could maintain the rate of advance of the tanks. *Though "blitzkrieg" is a German language word meaning "lightning war", the word did not originate from within the German military. It first coined by a journalist from the United States newsmagazine TIME describing the 1939 German invasion of Poland. Published on 25 September 1939, well into the campaign, the journalist's account reads: The battlefront disappeared, and with it the illusion that there had ever been a battlefront. For this was no war of occupation, but a war of quick penetration and obliteration—Blitzkrieg, lightning war. Swift columns of tanks and armored trucks had plunged through Poland while bombs raining from the sky heralded their coming. They had sawed off communications, destroyed stores, scattered civilians, spread terror. Working sometimes 30 miles ahead of infantry and artillery, they had broken down the Polish defenses before they had time to organize. Then, while the infantry mopped up, they had moved on, to strike again far behind what had been called the front. http://en.wikipedia.org/wiki/Blitzkrieg

WWII blitzkrieg German-style sprang from their spring offensives in WWI. Fast-moving groups of elite stormtroopers penetrated enemy lines after concentrated artillery fire blasted lanes through them. The stormtroopers' job was to keep moving forward; the following line infantry would reduce the enemy troops they left behind. In this sense, they played something like the same role that their cavalry, the Uhlans, had played in the Franco-Prussian War of 1870 - namely, a psychological as much as a military one. In WWII, the stormtroopers' role was filled by the armoured divisions, and the artillery's by the air force, especially the Stukas with their pinpoint bombing capability. They simply played the role of super-long-range artillery. A high degree of co-ordination between the various arms, and between units of the same arm (which, acting relatively independently, could easily get separated), was required. This was made possible by radio, without which the whole thing wouldn't have been possible, and by an organisation which made full use of its potential. Blitzkrieg as practiced by the Germans had flaws. Perhaps the main one was that the whole army wasn't motorised, with the result that the line infantry became seperated from the panzers. Hitler actually stopped Guderian on his rampage through France, on May 17th, because of his fear that the Allies would cut the panzers off from the following infantry. However, Guderian correctly judged the amount of psychological dislocation his advanced had caused, which was more than enough to throw the Allies into confusion, and managed to arrange matters so that his advance continued. I'd highly recommend Len Deighton's book "Blitzkrieg" as a thorough exploration of the subject. I'd also recommend Charles Messenger's "Blitzkrieg", which takes a much wider view. According to him, the true heirs of the blitzkrieg tradition were the Israelis, as they showed during their four wars with the Arab states.