The “Arab Awakening” heralds the breakdown of the republican political order established in the revolutionary upheavals of the 1950s and 1960s. The modern state of Yemen emerged in the context of an epic battle for legitimacy between the revolutionary republics headed by Egypt and the conservative monarchies headed by Saudi Arabia—a struggle carried out largely on the blood-soaked soil of Yemen from 1962 to 1967. In order to comprehend the republican meltdown of 2012, one needs to revisit Egypt’s crucial decision to send its armed forces to aid the fledgling Yemen Arab Republic in 1962. Surprisingly little scholarship exists on the Egyptian intervention in Yemen. Interpretations of Nasser’s decision to intervene have tended either to blame Egypt for premeditated aggressive expansionism or to exculpate Egypt for selflessly reacting to Saudi meddling in the internal affairs of a sister Arab state. A careful review of newly available evidence, including recent Egyptian and Yemeni memoirs and declassified documents from Russia, the United States, and Israel, reveals a more complicated truth. On the one hand, the intervention had deep roots in Egypt’s traditional support for nationalist revolutionaries. That commitment pertained especially to Yemen, situated strategically in the backyard of Egypt’s emerging rival: the oil monarchy of Saudi Arabia. Yet Egypt was not planning a military campaign in 1962. On the contrary, the Egyptians responded impulsively, on the basis of incomplete information, to the news of the coup d’état in ?an‘?’ in late September 1962. The coincidence of the coup with a struggle for power within the Egyptian regime contributed to the hasty adoption of half-way measures, generating unintended escalation. As Nasser later remarked: “I sent a company to Yemen and had to reinforce it with 70,000 men.” The quagmire that ensued carried major implications for Yemen, for Egypt, and for the region. In an effort to secure their regime against internal opposition, the Yemenis ended up building a police state plagued by many of the problems that afflicted Egypt and the other Arab republics in the decades since. The war accelerated a number of negative trends in Egypt itself, including runaway defense spending, rampant corruption, and decreasing tolerance for dissent. These and other factors did much to discredit Arab nationalism and the republican model of government. In retrospect, 1962 marked both the birth of modern Yemen and the distant origin of the Arab Spring.