World War I devastated European Jewry, forcing the great men of the generation to act. The Chazon Ish preferred to work behind the scenes, but his mentors, the Chofetz Chaim and Rabbi Chaim Ozer Grodzensky, urged him center-stage. Rabbi Wein follows the Chazon Ish’s ascent to leadership - from war-torn Vilna to the nascent town of Bnei Brak.