In 1940, Mussolini took his country into World War II on the side of Nazi Germany but soon was met with military failure. By the autumn of 1943, he was reduced to being the leader of a German puppet state in northern Italy and was faced with the Allied advance from the south and an increasingly violent internal conflict with the partisans. In April 1945, with the Allies breaking through the last German defences in northern Italy and a general uprising of the partisans taking hold in the cities, Mussolini's situation became untenable.