There’s a sort of a misconception I want to address before answering the meat of the question. The “Blitzkrieg tactic” is not so much a tactic but a doctrine on how to fight. In any given battle, “Blitzkrieg” would have looked different from another battle; the unifying aspect was aggressive maneuver aiming to encircle the enemy. However, more to the point, it’s not clear that a coherent “Blitzkrieg” theory even existed. Several modern historians (Robert Citino, Shimon Naveh, and Michael Geyer come to mind) have made very compelling cases that “Blitzkrieg” is an after-the-fact invention by various parties. What certainly did exist was a general way of war that promoted aggression, rapid and clever maneuver, and the goal of encircling the enemy to destroy his armies.

With that in mind, how did Nazi forces avoid being encircled? Generally, the Germans sought to break through enemy lines into the open, loosely defended terrain behind the lines - the operational or strategic depths. Once in these depths, the Germans used the high maneuverability of their panzer divisions to prevent enemy reserve formations from pinning them in place. Multiple breakthroughs would meet up in the depths (the classic “double pincer”) and complete the encirclement. In some cases, terrain was used as the second pincer. In either case, the rapid deep penetration creates confusion in the defender’s commanders. Real war is not like an RTS game, where you can see all the forces moving in real time and perfect detail on the map; commanders have to make do with the information they have, and it is usually hard to have good information on enemy maneuver forces in your rear areas. This makes it harder to encircle the attacking breakthrough forces before they complete their own encirclement of the defenders, and receive reinforcements through the gap they’ve created in the enemy lines. The chaos of a breakthrough also takes a toll on the defenders, particularly in the conditions of so-called Blitzkrieg. One tank commander recalled this from the Allied defense of Greece: “From dawn to dusk there was never a period of more than half an hour when there was not an enemy plane overhead. It was the unrelenting pressure of noise and the threat of destruction in every hour which accentuated the psychological consequences of continuous retreat, and turned so many men into nervous wrecks who leapt from their driving seats and trucks at the first distant hum—often without stopping their vehicles—and ran from the roads . . . not to stop running until the skies were clear and the explosions had ceased to echo in their minds. Then they would make their way slowly, fearfully, back and ride on for another few miles until the next raid, or threat of a raid, set them running again.”

The key to this method of achieving the encirclement is mobility. The Germans enjoyed superior mobility over the armies they faced early in the war, for various reasons. Some armies, like the Yugoslavians and Poles, dug in across their entire border, resulting in lines that were too thin to absorb a concentrated German blow and depriving themselves of adequate mobile reserves in the rear. Others, like the French, fell victim to strategic surprise (in the case of the panzer attacks through the Ardennes Forest) in addition to their broad, thin lines. However, once mobility broke down, the weakness of a breakthrough-heavy doctrine became apparent. The Soviets were the first to really master the defense in depth, and it showed most clearly at Stalingrad. 4th and 6th Panzer Armies were unable to break through the Soviet lines at the Volga river, and, having become embedded in the city, fell victim to a highly mobile Soviet counterattack and were encircled.

######Sources:

Citino, Robert. Death of the Wehrmacht: The German Campaigns of 1942. Lawrence, KS: University Press of Kansas, 2007.

Naveh, Shimon. In Pursuit of Military Excellence: The Evolution of Operational Theory. Portland, OR: Frank Cass Publishers, 1997.