On 18 January 1943, the Germans began their second deportation of the Jews, which led to the first instance of armed insurgency within the Ghetto. While Jewish families hid in their so-called “bunkers”, fighters of the ŻZW, joined by elements of the ŻOB, resisted, engaging the Germans in direct clashes.Though the ŻZW and ŻOB suffered heavy losses (including some of their leaders), the Germans also took casualties, and the deportation was halted within a few days. Only 5,000 Jews were removed, instead of the 8,000 planned by Globocnik. Hundreds of people in the Warsaw ghetto were ready to fight, adults and children, sparsely armed with handguns, gasoline bottles, and a few other weapons that had been smuggled into the Ghetto by resistance fighter. Most of the Jewish fighters did not view their actions as an effective measure by which to save themselves, but rather as a battle for the honor of the Jewish people, and a protest against the world’s silence. Two resistance organizations, the ŻZW and ŻOB, took control of the Ghetto. They built dozens of fighting posts and executed a number of Nazi collaborators, including Jewish Police officers, members of the fake resistance organization Żagiew, as well as Gestapo agents.
On 19 April 1943, on the eve of Passover, the police and SS auxiliary forces entered the Ghetto. They were planning to complete the deportation action within three days, but were ambushed by Jewish insurgents firing and tossing Molotov cocktails and hand grenades from alleyways, sewers, and windows. The longest-lasting defense of a position took place around the ŻZW stronghold at Muranowski Square, where the ŻZW chief leader, Dawid Moryc Apfelbaum, was killed in combat. On the afternoon of 19 April, a symbolic event took place when two boys climbed up on the roof of a building on the square and raised two flags, the red-and-white Polish flag and the blue-and-white banner of the ŻZW. These flags remained there, highly visible from the Warsaw streets, for four days. When Stroop’s ultimatum to surrender was rejected by the defenders, his forces resorted to systematically burning houses block by block using flamethrowers and fire bottles, and blowing up basements and sewers. While the battle continued inside the Ghetto, Polish resistance groups AK and GL engaged the Germans between 19 and 23 April at six different locations outside the Ghetto walls, firing at German sentries and positions. The suppression of the uprising officially ended on 16 May 1943, when Stroop personally pushed a detonator button to demolish the Great Synagogue of Warsaw. Sporadic resistance continued and the last skirmish took place on 5 June 1943 between Germans and a holdout group of armed Jews without connections to the resistance organizations..