Warsaw Ghetto Insurgency Begins (1943)
On January 18, 1943, the Germans began their second deportation of Jews from the Warsaw Ghetto, which led to the first instance of armed resistance. The deportation was halted within a few days; only 5,000 Jews were removed instead of 8,000 as planned. The Nazis retreated, only to return three months later, at which time the Warsaw uprising started in earnest.
Link: Warsaw Ghetto Uprising