Kammala wannan jumla: An haife shi a Ain al-Remaneh tare da asalinsa daga Bsharri, Geagea ya shiga Jam'iyyar Kataeb a farkon shekarunsa. A shekarar 1978, a lokacin yakin basasar Lebanon, ya shiga cikin
Kisan gillar Ehden, inda ya jagoranci dakarun da suka kashe Tony Frangieh, shugaban kungiyar 'yan bindiga ta Marada, da danginsa. Ya shirya juyin mulki tare da Elie Hobeika da Karim Pakradouni a shekarar 1985 a kan umarnin Fouad Abou Nader. Tare da goyon bayan Shugaba Amine Gemayel, Geagea ya shirya juyin mulki na biyu, bayan Hobeika ya rattaba hannu kan Yarjejeniyar Tripartite tare da Nabih Berri da Walid Jumblatt.