My dissertation views Lebanon as an important setting for competing networks of revolution, counterrevolution, and empire on local, regional, and global scales in the second half of the 20th century. While treated as an internal conflict in the existing literature, the growth, transnational circulation, and demise of the war's opposing political camps involved far more than Lebanese politics. Lebanon's liberal political structure and laissez-faire economy made it a site of contention for nearly all regional political forces after the 1967 Arab defeat. The PLO, revolutionary Arab nationalists, and Marxists thrived in this period, steering domestic opposition in Lebanon into a reservoir for armed struggle against "imperialism, Zionism, and Arab reaction." In response, their diverse opponents mobilized into counterrevolutionary political and military units to purify the nation from the "international leftist conspiracy." US policy, meanwhile, stressed upholding Lebanon's pro-Western alignment in what appeared as an increasingly hostile Arab region. The encounter between these rival networks erupted into civil and international war in 1975 and endured until the end of the Cold War. Drawing on Lebanese, Palestinian, American, and British archives, unpublished papers, pamphlets, and media reports in Arabic, English, and French, I explore how Middle Eastern actors employed and transformed transnational discourses and networks of conflict, while arguing the war was a crucial setting for the US and its allies after Vietnam. Using what I call the "Third World War" as a conceptual framework, I track the linkages between people, materiel, and ideas across sites of conflict, enabling a rethinking of the Cold War as an international civil war connecting actors in numerous states, and often driven by events in the "periphery." My dissertation thus meshes the history and historiography of Lebanon with that of the greater Middle East, decolonization, and the global Cold War.