Joined Betar and was active in the illegal immigration movement, and for two years (1937-1939) accompanied immigrant ships to Eretz Israel.
In 1939 came illegally to Eretz Israel and joined the Betar Company at Rosh-Pina where he became an Irgun member.
In 1941 he joined the British Army and served in Egypt and Italy.
After the Second World War he studied physics both at the University of Florence and later at the Hebrew University of Jerusalem.
In January 1948 was sent to the Old City as the commander of the Irgun in the Jewish Quarter. After the British left Jerusalem, he fought against the Arab invaders valiantly and set a very courageous example. He was severely wounded, yet went on fighting. Was taken prisoner to Jordan, and on coming back after the war he joined the Department of Physics at the Hebrew University of Jerusalem.