July 15, 1958: Lebanon's Christian and Muslim factions engage in civil war.
With Egypt and Syria's pan-Arab movement stirring up sentiments among Lebanon's religious groups, Lebanon's fragile coalition government weakens. The Lebanese army's loyalty to President Kamil Shamun wavers. With the outbreak of civil war between Christians and Muslims, Shamun calls on the U.S. to send troops to secure peace. The U.S., wanting to avoid another coup (as had just occurred in Iraq), sends 5,000 Marines to Lebanon.