Yitzhak Shamir was an Israeli politician and the seventh Prime Minister of Israel, serving two terms, 1983–1984 and 1986–1992. Before the establishment of the State of Israel, Shamir was a leader of the Zionist militant group Lehi. After the establishment of the Israeli state he served in the Mossad between 1955 and 1965 and as a Knesset Member. He served as the sixth Speaker of the Knesset, and as Foreign Affairs Minister. Shamir was the country's third-longest-serving prime minister, after Benjamin Netanyahu and David Ben-Gurion.