During the uprising, well-armed fighters of the Jewish Military Union put up a tenacious, three-day-long defence of Muranowski Square.
According to the account of Emanuel Ringelblum, their ammunition store – located at the headquarters at Muranowska Street – contained machine guns, revolvers, rifles, hand grenades, bags full of ammunition, and German uniforms. They were also properly prepared, because Betar placed particular emphasis on military training.
After the start of the battle, the fighters hung two flags on the tenement house at Muranowska Street: one Jewish and one Polish. One Nazi officer died in the assault on the building. The Jewish Military Union had previously made plans for withdrawing from the ghetto. Once the fighting in Muranowski Square drew to a close, the insurgents exited in several groups. An account written by “Rudy Paweł” provides us the details of one such escape. A group of insurgents from the Jewish Military Union was hiding in the forests near the village of Mlądz. They were waiting to be contacted by the Home Army, whose soldiers were to help transfer them to partisan units. Before this happened, however, the group was discovered and informed on by a blue policeman. Most of its members died in the ensuing clash with the enemy, although some managed to return to Warsaw before the group was exposed, however they perished before the liberation, most probably during the Warsaw Uprising.