Autumn rain fell briefly on Hostages Square in Tel Aviv on Thursday morning. Despite the clouds hanging gray and low over Israel’s coast, the mood was anything but dark. As hostage families and their supporters finally allowed themselves to smile after two years of anguish, the downpour seemed to wash away at least some of the anger and pain that marked the war that broke out with Hamas’s invasion of southern Israel two years ago. Assuming there is no eleventh-hour surprise that blows up the process, Israelis will welcome their 20 living hostages home, and see the return of most...