JERUSALEM — An abiding image of the former Israel defense minister Amir Peretz was a photograph of him peering at a military drill — with the black lens caps still on his binoculars. Mr. Peretz resigned months after the 2006 war in Lebanon, which was widely regarded as a failure. Yet on Sunday, as rockets fired by Gaza militants streaked toward Tel Aviv, Ashdod and other Israeli cities, Mr. Peretz, a resident of the rocket-battered border town of Sderot, was being hailed as a defense visionary for having had the foresight while in office to face down myriad skeptics and...