What was the period of time During the winter time of 1939-40 when there was when there was little activity in the west Known as?

The period of little activity in the west during the winter of 1939-1940 is known as the "Phoney War" or "Sitzkrieg." It refers to the lack of major military operations on the Western Front after the German invasion of Poland in September 1939 and before the Battle of France in May 1940.