The Warsaw ghetto contained only 60,000 Jews by the end of 1942. When these survivors learned the truth about Treblinka, young Jewish men and women from the ranks of the Zionists and Socialists formed a resistance group known as the Jewish Fighting Organization, or Z.O.B. The Z.O.B. was commanded by Mordechai Anielewicz, a twenty-three year old Zionist, and numbered about 800 fighters.

The Z.O.B. urged the Jews remaining in the Warsaw ghetto to refuse deportation and to go into hiding. They built underground hiding places where they stored food and water. They also appealed for weapons to the Polish resistance (known as the Home Army). After repeated pleas, the Home Army agreed to sell the Z.O.B. a limited amount of arms.

The battle of the Warsaw ghetto began on April 19, 1943. A force of 2,000 Nazi SS troops attacked the ghetto with tanks and machine guns. They were met with gunfire and temporarily driven out. SS General Stropp ordered the ghetto set on fire with artillery and flamethrowers. The fighting raged for weeks until Jews ran out of ammunition. Thousands died in the burning buildings.

On May 8, 1943, the Germans discovered the underground headquarters of the Z.O.B. Nazi explosives killed Mordechai Anielewicz and one hundred of his comrades.

The Warsaw ghetto uprising ended on May 16, 1943. 7,000 Jews died during the revolt. Only seventy Jewish fighters were able to escape. The Germans immediately deported the remaining Jews to the death camp at Treblinka.