(4) Civil wars with lots of factions last longer than average. Barbara F. Walter of the University of California at San Diego points to a 2006 paper in the Journal of Political Science arguing that civil wars last longer when there are more competing factions. The number of rebel groups tends to change on a pretty regular basis, but Walter says there are 13. Whatever your count, there are a lot of them, their alliances and allegiances tend to change a lot and, most worrying, they’re already fighting one another.

(5) Civil wars are longer than average when no side can disarm the other. It’s not just about seizing and holding territory: it’s about taking away your opponent’s ability to fight you. “Civil wars tend to last a long time when neither side can disarm the other, causing a military stalemate,” Fearon concluded in his 2002 study. The Assad regime is actively armed by a foreign power, Iran, which suggests it would be really difficult for the rebels to disarm them. And it’s hard to see how Assad could ever disarm the rebels, who come both from within the Syrian population and from across the border in Iraq, given both the popular outrage against his regime and the ease of acquiring weapons.