What tactic was primarily used by German forces during their invasion of Poland in 1939?

The tactic primarily used by German forces during their invasion of Poland in 1939 was Blitzkrieg, which translates to "lightning war." This military strategy focused on rapid, surprise attacks that combined air and ground forces to quickly overwhelm the enemy. The Germans utilized coordinated assaults involving aircraft (for air superiority and ground support), tanks (for fast and penetrating ground assault), and infantry (to secure the areas gained).

Blitzkrieg aimed to produce quick victories and minimize prolonged engagement with the enemy, which was particularly effective in the flat terrain of Poland. This approach allowed Germany to invade and conquer Poland efficiently within a matter of weeks, demonstrating the effectiveness of modern mechanized warfare and leading to significant changes in military tactics in the years that followed.

Other options represent different types of military strategies that were not the primary focus during the Polish campaign. For example, siege warfare typically involves surrounding and isolating an enemy to force a surrender, which was not the approach taken in this rapid invasion. The pincer movement, while a tactical maneuver used in broader military strategies, does not encapsulate the entirety of Blitzkrieg's principles. Attrition, which suggests wearing down the enemy over time, was also not the intention behind the swift actions in Poland.