Blitzkrieg was a tactic of using mechanized warfare combined with shock troops. This method of warfare was employed by Nazi Germany against Poland, France, the Low Countries, and the Soviet Union. Thanks to superior officer training, German officers were trained to exploit opportunities on the battlefield where they appeared, provided that these tactics fit into the overall battleplan. German air cover meant to neutralize the other country's air support systems and to support Nazi combat troops with dive bombers and strafing attacks. German mechanized units (tanks) were not heavily armored, but relied more on speed in order to assist and support the ground troops. Germany also made good use of paratroopers in order to secure transportation hubs for the army to advance.
Blitzkrieg worked well against the static defenses of France and the Low Countries and against the poorly prepared air defenses of Poland and the Soviet Union. It did have its shortcomings--it was powerless in urban areas, and bogged down around Leningrad and Stalingrad, which ultimately proved to be fatal to the German empire. Also, this method of war relied heavily on maintaining mechanized equipment--the German empire was very reliant on fuel and oil resources, which by 1942 were in scarce supply.