Born in Ain al-Remaneh with origins from Bsharri, Geagea joined Kataeb Party in his early years. In 1978, during the Lebanese Civil War, he participated in the Ehden massacre, where he led troops that killed Tony Frangieh, leader of Marada militia, and his family. He organized a coup alongside Elie Hobeika and Karim Pakradouni in 1985 against Fouad Abou Nader's command. Supported by President Amine Gemayel, Geagea organized a second coup, after Hobeika signed the Tripartite Accord with Nabih Berri and Walid Jumblatt.