Turkey has announced the start of Operation Euphrates Shield, an offensive led by Syrian rebels to retake territory on the Syria-Turkey border from the Islamic State. The most important target of the operation is the town of Jarabulus, the last major Islamic State stronghold in the border region. With artillery and airstrikes, Turkey launched a concerted bombardment on nearly 100 Islamic State targets Aug. 24, clearing a path for the rebels to begin their attack on Jarabulus. After several hours of light fighting as the Islamic State retreated, the rebels succeeded in recapturing the town....