The Prophet Muhammad died in 632 AD. Who should succeed him as “caliph,” the leader of the Faithful? Should the succession be “elective” in the sense of someone chosen from among Muhammad’s chief followers? If so, then the leading candidate was Abu Bakr, Muhammad’s father-in-law and a powerful prop of Islam. Or should the succession be “hereditary” in the sense of someone chosen from among Muhammad’s sons-in-law so that the blood of the Prophet would run in the veins of future caliphs? If so, the leading candidate was Ali, the favored son-in-law. The majority supported the “elective” solution: Abu Bakr became the caliph. Ali and his followers sulked and schemed. Eventually Ali seized power as the fourth caliph, only to be assassinated. Since the debate over the succession, Islam has been split between a majority which sprang out of the supporters of Abu Bakr, the Sunni, and a minority that sprang from the “party of Ali,” the Shi’a[t Ali]. Eventually, the caliphate passed to the Ottoman sultan. The majority of Ottoman subjects were Sunni Muslims, with Shi’ites a minority located in what would become Syria and what would become Iraq. The great majority of Shi’ites were found in Persia/Iran.
Events in the 1980s turned up the flame under this conflict. The Iranian Revolution led to the creation of a revolutionary theocratic republic. Saddam Hussein’s attack on Iran led to a long war in which other Sunni states supported Iraq. Iran largely created the Hezbollah movement in Lebanon.
At the start of the Twenty-First Century, Syria under the Assad dictatorship offered a mirror-image to Iraq under the Hussein dictatorship. In the former, a Shi’a minority ruled a Sunni majority in the latter, a Sunni minority ruled s Shi’a majority. The overthrow of these regimes then opened the door for the oppressed minorities to seek revenge. Since the beginning of the Syrian civil war in March 2011, the Assad government has seen half the country secede from its control. In Iraq, the Maliki government got right to business as soon as they had waved good-bye to the all-too-willing Americans in 2011.
Both sides in the Syrian civil war have found supporters among their co-religionists abroad. Shi’ite Iran and the Shi’ite government of Iraq have aided the Shi’ite Assad government. Sunni Qatar, Sunni Saudi Arabia, and Sunni foreign fighters have supported the Sunni Islamists who are doing most of the heavy lifting against the Assad government in Syria and who have attacked the Shi’ite government in Iraq. (See: “A Dog in This Fight?”)
“The Sunni-Shi’ite War,” The Week, 1 November 2013, p. 9.
 Wait. They’re fighting a gory war over something that happened 1400 years ago? Well, not exactly. During the 1400 years the two sects developed different religious practices which divide them. They also developed a history of conflict, oppression, and resistance linked to these two different faith traditions. So, they’re fighting a gory war over stuff that began 1400 years ago and continued—in widely varying degrees of intensity—down to the present. It probably isn’t helpful to try to analogize it to history-based conflicts in Western culture, like Protestant versus Catholic in Northern Ireland or the struggle for African-American civil rights.
 Do minorities create dictatorships as a defensive response to past or potential threats from the majority? That’s a political science question, rather than a historical question.
 While effete Italians assert that “revenge is a dish best tasted cold,” Arabs appear to prefer take-out.
 Is it possible to compare the Syrian Civil War to the Spanish Civil War? Or aren’t young Muslims entitled to a romantic commitment to an idealistic cause that subsequently turns out to be soiled by Great Power scheming?