Sitzkrieg

Sitzkrieg is lack of aggression in war, a pun on the opposite term blitzkrieg. Sitzkrieg is easy to remember with the prefix "sit" ("sitz" in German), representing sitting around rather than going into battle. A synonym is "phony war."

Sitzkrieg was coined to describe the inactivity in late 1939 and early 1940, the early phase of World War II, after Germany did its blitzkrieg in Poland.