Menachem Begin was born in Brest-Litovsk in 1913 and led the Betar youth movement in Poland. After reaching Eretz Yisrael during World War II, he commanded the Irgun underground. After the founding of the State he founded and led the Herut party, and for nearly three decades headed the parliamentary opposition. In 1977 he became Prime Minister, serving until 1983; he signed the peace treaty with Egypt and shared the 1978 Nobel Peace Prize. He was known for his warm regard for Jewish tradition, and he visited the Rebbe at 770 in 1977.
Some of these letters touch on political questions; they present the Rebbe's own position.
Unity and Jewish identity. The Rebbe wrote to Begin that Jewish unity must be preserved even in times of discord and external hatred (IK 8431), that Shabbos observance both preserves Jewish spiritual life and unites diverse communities (IK 7724), and that amid challenges to faith one must reveal each Jew's inner essence through personal connection (IK 8399).
Outreach and Torah. He encouraged outreach and teshuvah activities, especially among youth (IK 8580), support for sincere students wishing to study Torah abroad (IK 9828), and ongoing positive action and cooperation for the benefit of the Jewish people in Eretz Yisrael and throughout the world (IK 9637).
Sources: Wikipedia ("Menachem Begin"); and the Rebbe's letters cited above.