Haika Grossman participated in the “movement” at a gathering in a convent near Vilna, where the group, led by Abba Kovner (1918–1988), decided on armed resistance. Sent to Bialystok to organize the fighting underground, she served as a contact person between Vilna and Bialystok and other ghettos. Her “ammunition” was resourcefulness, arrogance, courage, strong nerves and constant alertness, all of which saved her from virtually hopeless situations. “
Between August 1943 and August 1944, Grosman participated in forming a group of six women in Bialystok, called “the anti-fascist committee.” The aim of their hazardous activity was the ongoing maintenance of contact with the Soviet partisan brigade in the forest. They led Jews to them, established relations with anti-fascist Germans in the towns, and used their help to acquire ammunition for the underground and the partisans. With the surrender of the German troops, Grosman and her friends marched in the front line, side by side with the Soviet Brigade fighters that entered the city in August 1944.