The Prophet Muhammad preached a Muslim world undivided by politics. This meant that there would be a single “caliphate that governed all Believers, and that politics and religion would be inseparable. Despite the compelling power of his beliefs, he did not get what he wanted. After Muhammad’s death (632 AD), Sunni contested with Shi’ites, and the “umma” fractured into rival states. This unhappy condition continued from the 8th Century to the 21st.
After the Second World War, Muslim states gained true independence, but as separate nations. The rivalries between them continued. In particular, dictatorial republics contended with authoritarian monarchies. From 1952 to 1970, Egypt’s populist dictator Gamal Nasser tilted with Saudi Arabia. Nasser inspired unrest where he could; conservative monarchies fought back as best they could. The larger struggle came to be called “The Arab Cold War.”
Yemen provided one spot where this “Cold War” turned hot. In 1962, followers—or agents—of Nasser overthrew the hallowed-by-time imamate in North Yemen. Supporters of the traditional monarchy fought back. The ensuing civil war ran until 1970. Roughly, tribesmen in the north supported the monarchy, while people in the slightly-more-urban south supported the Nasserites/republican rebels. Nasser’s Egypt sent forces—especially bombers—to support the rebels forces, although 70,000 Egyptians ended up serving in Yemen at the height of the Egyptian intervention. The Egyptian forces proved no more effective at counter-insurgency warfare would Western troops in Afghanistan or Vietnam. Britain, Israel, Saudi Arabia, and Iran joined in the war—albeit clandestinely—against the Nasserites. All had their motives. Britain. For example, was obsessed with Nasser’s defiance of Britain in the 1956 Suez Crisis, and hoped to reduce Egyptian influence in the Middle East. Israel, for its part, saw getting Egypt bogged down in southern Arabia as a good means of reducing Egypt’s support for cross-border raids in the Sinai and elsewhere. At the same time, the Israelis were alarmed by Egypt’s development of a “weapon of mass destruction”—poison gas—and this may have contributed to the decision to attack the surrounding Arab vulture states in 1967.
As a result, the war dragged on—inhumanely, but little noticed in the West–for eight years. In the meantime, international humanitarian non-governmental organizations (NGOs) like the International committee of the Red Cross and the Southern Baptist Convention in the United States involved themselves in humanitarian aid. The need was great. Wars fought in less developed countries tend to wreck the feeble infrastructure and medical support.
In the end, backed by Egypt, the republican Yemenis won the civil war. They constructed the façade of a “modern” nation. However, many of the tribesmen in northern Yemen remained unreconciled to that new state. They bided their time in preparation for a new round of conflict. This week-end, the New York Times ran a story on famine in Yemen, where a new civil war has provided a proxy for the on-going Saudi Arabian-Iranian struggle for power.
 See: Malcolm Kerr, The Arab Cold War: Gamal ‘Abd al-Nasir and His Rivals, 1958-1970 (1971). It is a brief, but well-informed journalistic account. It was new when I was in grad school.
 Asher Orkaby, Beyond the Arab Cold War: the International History of the Yemen Civil War, 1962-1968 (2017).
 It was asserted that Egyptian troops used poison gas against their foes.
 The story itself was excellent, but the headline elided the reality that “it takes two to tango.” As in Syria, the wars and suffering would end if the “good guys” (in Western eyes) stopped fighting wars they cannot win.