In the worst times, people fought back: 

 The Bund created youth groups, newspapers, illegal schools, and a courier service that transmitted news across occupied Poland; the latter’s operatives exchanged information at soup kitchens that the Bund set up as cover. Money came from New York-based organizations like the Jewish Labor Committee (founded by Vladeck), smuggled by Jewish girls pale enough to pass as Polish gentiles. Later, that money paid for hiding places and guns. After October 1940, when Nazis began herding Warsaw’s Jews into the Ghetto, the Bund organized the teeming tenements into committees dedicated to cultural, as well as physical, survival.

[…]

The Bund’s long relationship with Polish socialists allowed them to breach the ghetto walls, sneak in Polish resistance soldiers, and provide the world with some of the first accounts of the Nazi genocide, through the testimonies of Zalman Freidrych and Jan Karski. Through these networks, news filtered out, and weapons flowed in. In April 1943, three months after the first brief battle of the Warsaw Ghetto Uprising, one final arms shipment smuggled by Bundists got through the Ghetto walls.

How many Nazi troops died in that doomed revolt is still disputed. Three hundred, according to Bundist Marek Edelman, who assumed command of the ZOB, after its first leader committed suicide to avoid surrender. Sixteen, claimed the SS commander Jürgen Stroop, who had every reason to suppress the true figures. What is known is that it took the most feared military force in Europe three weeks to subdue 750 starving, inadequately-armed captives. Even then, the ghetto fell not to fighting, but to fires, set by German flamethrowers and incendiary bombs. Some 13,000 Jews died in the rebellion. In London, Artur Ziegelboim, the Bund’s representative in the Polish parliament in exile, took poison in a futile attempt to rouse the world from its indifference. The words of his suicide note read: “I love you all. Long live the Bund.”

Emphasis mine. Read the whole thing.

A.