Future Israeli Prime Minister Menachem Begin, who had headed Betar Poland prior to World War II, reached Palestine at the war's end and took immediate control of both Betar Palestine and the Irgun. He led the two organizations in their contribution to the 1948–49 war that established the initial borders of the newly proclaimed state of Israel. Betar and the Irgun remained functionally intermingled, consistently sharing leadership and manpower. By contrast, the Haganah, the official defense organization of the Jewish Agency, and its military wing, the Palmach, had practically no Betar members.