Final answer:
A 'blitzkrieg' is best defined as a rapid and overwhelming military attack by air and land, aimed at quickly defeating the enemy with speed and force, and was notably used by Germany in WWII.
Step-by-step explanation:
The best definition of a "blitzkrieg" is a rapid invasion by air and land, involving an all-out, quick concentrated attack to overwhelm an enemy. This military strategy was used by Nazi Germany, most notably at the beginning of World War II.
The term "blitzkrieg" translates to "lightning war" in English, and it describes a method of warfare wherein the attacker unleashes a powerful initial offensive to break the enemy's defenses through a combination of speed, surprise, and overwhelming force. This includes massive air strikes to gain air superiority, destroy infrastructure, and demoralize the enemy, followed by swift movements of tanks and motorized infantry to encircle and defeat enemy forces. The Polish campaign in September 1939 serves as a prime example of this strategy, which led to the rapid defeat of Poland.