Before the creation of the state of Israel, he was the leader of the Zionist militant group Irgun, the Revisionist breakaway from the larger Jewish paramilitary organization Haganah. He proclaimed a revolt, on 1 February 1944, against the British mandatory government, which was opposed by the Jewish Agency. As head of the Irgun, he targeted the British in Palestine.
Begin’s government promoted the construction of Israeli settlements in the West Bank and the Gaza Strip. Begin authorized the bombing of the Osirak nuclear plant in Iraq and the invasion of Lebanon in 1982 to fight PLO strongholds there, igniting the 1982 Lebanon War.
As Israeli military involvement in Lebanon deepened, and the Sabra and Shatila massacre, carried out by Christian Phalangist militia allies of the Israelis, shocked world public opinion .... http://en.wikipedia.org