From the onset of German-Soviet conflict in 1941, Communist parties throughout Europe were notable for their active and dominant in local resistance against Nazi occupation.
After September 1943, partisan Resistance groups were active throughout northern and much of central Italy. Many were recruited, organized, and armed by the anti-Fascist parties or at least owed vague allegiance to one of them. Partisans were fighting three types of war: a civil war against Italian Fascists, a war of national liberation against German occupation, and a class war against the ruling elites. Communist Party groups fought all three types. Catholic or monarchist partisans, on the other hand, fought only one or two of these.
The Communist Party, although still very small in 1943 (about 5,000 members), led the largest group of partisans (at least 50,000 by summer 1944). Success in the Resistance transformed the Communists into a major force in postwar Italian politics. After the war, the three largest parties were the Christian Democrats, Socialists, and Communists.
Individual Jews or groups of Jews engaged in planned or spontaneous opposition to the Germans and their allies. Jewish partisans were especially active in the east, where they fought the Germans from bases established behind the front lines in forests and ghettos. Because antisemitism was widespread there, they found little support among the surrounding population. Even so, as many as 20,000 Jews fought the Germans in the forests of eastern Europe.
Until June, 1941, when Hitler invaded the Soviet Union, there was no resistance at all inside France. The majority of the French supported the pro-Fascist Vichy government of Marshal Henri Petain. De Gaulle discouraged acts of terrorism by his followers for fear of reprisals against innocent civilians. The Communist Party was not going to attack Germans so long as the Soviet Union had a nonaggression treaty with Germany.
After the Nazis invaded the Soviet Union, however, the Communists began the French Resistance. A large number of their recruits were young immigrants, many of them workers with Communist backgrounds.