When World War II erupted, she moved to Wilno (now Vilnius, Lithuania), where she was active in the emergency underground leadership of HaShomer HaTzair.

Her Polish identity enabled her to assist the underground movements in numerous towns and ghettoes, as well as the emerging partisan units being formed in the nearby forests of Poland and Lithuania.

After the war, Grossman served on the Central Committee of the Jews of Poland, and was awarded medal for outstanding heroism.

In 1993, Grossman was invited to light one of twelve torches traditionally kindled in the national ceremony marking Yom Ha'atzma'ut (Israel's Independence Day).

Later, at a party for the torch lighters, she slipped down a flight of stairs and fell into a coma, which lasted three years, until her death in 1996.