During the 1929 Arab riots, took part, as a member of the Haganah, in the defence of Jerusalem.
Was an activist and joined the Irgun when Tehomi founded it.
Together with David Raziel, wrote the book "The Revolver" and ideological articles on liberation and underground movements, as well as poems. His poem "Hayalim Almonim" ("Unknown Soldiers") became the anthem of the Irgun and Lehi.
Studied at the Hebrew University of Jerusalem, completed his studies cum lauda, and received a scholarship to study Greek and Roman at Florence University, Italy.
In 1933 broke off his studies and devoted himself to underground activity in Eretz Israel.
In 1939 differences of opiniion emerged between Stern and Raziel, then commander of the Irgun, which led to a split in the organization and the establishment of the new organization Irgun Zvai Leumi Beisrael, which became Lohamei Herut Yisrael (Lehi).
Murdered by the British on February 12, 1942.