Final answer:
The early months of World War II were marked by a period known as the 'Phony War', followed by Germany's successful blitzkrieg campaigns which led to the fall of France.
Step-by-step explanation:
The early months of World War II were characterized by a period called the 'Phony War'. After the German conquest of Poland in September 1939, there was a lack of major military action in Europe. This period of calm was shattered in April 1940 when Germany launched a series of successful blitzkrieg campaigns, swiftly conquering Denmark, Norway, the Netherlands, Belgium, and finally France. The fall of France led to the establishment of the fascist Vichy regime in the country.