The "Phoney War" refers to a period early in World War II, between September 1939 and April 1940, during which very little military activity occurred at an international level. This period followed Nazi Germany's successful blitzkrieg attack on Poland in 1939.
During the "Phoney War," the Germans sent occupying forces to Poland. Other than that, however, minimal military activity occurred in Europe. Although British planes flew over Germany during this period, the planes did not drop bombs; they dropped propaganda leaflets for the German populace. The first use of the term "Phoney War" was credited to an American senator. In Germany, the time period was referred to as the "Sitzkrieg," which translated into English as the "sitting war."