Two years ago, joining a crescendo of protest around the Arab world, Syrians launched a peaceful uprising against the autocratic rule of Syrian President Bashar Assad. That dissent—met by a brutal government crackdown—has morphed into a bitter, grinding civil war between a fraying regime and a patchwork of rebel forces. The U.N. claims more than 70,000 people have died in 24 months of bloodshed, while the chaos has made over a million Syrians refugees.