Final answer:
Germany under the Schlieffen Plan aimed to defeat France within six weeks during World War I. In World War II, France fell after a few weeks due to Hitler's blitzkrieg tactics. However, in both wars, Germany's assumptions led to extended conflicts beyond their initial estimations.
Step-by-step explanation:
The German military strategy during World War I, known as the Schlieffen Plan, aimed to quickly defeat France within six weeks before turning to face Russia. The rationale behind this was based on the assumption that Russia would take longer to mobilize its forces. Despite meticulous planning, several factors such as the unexpected resistance from Belgium and France, the rapid mobilization of Russian troops, and the British Expeditionary Force's intervention, led to the failure of this plan. The war evolved into a series of protracted trench battles, with armies locked in a stalemate, a far cry from the swift victory Germany had anticipated.
In World War II, despite initial successes in bypassing the heavily fortified French-German border through a blitzkrieg that led to the rapid fall of Denmark and Norway, the failure to anticipate the fortitude of Allied resistance once more led to a protracted conflict. Hitler's aspirations to quickly defeat France were partly realized in 1940 when France capitulated after a few weeks of fighting. However, the assumption that the Maginot Line and other defensive measures could be easily bypassed without substantial resistance turned out to be a critical miscalculation once the conflict expanded globally.