WASHINGTON – President Barack Obama went for the defining television shot in Iraq and got it — pictures of hundreds of U.S. troops cheering wildly as he told them it was time for the Iraqis to take charge of their own future. The war zone photo opportunity produced a stunning show of appreciation for Obama from military men and women who have made great sacrifices, many serving repeated tours in a highly unpopular war. And the televised outpouring of affection likely will prove critical to the credibility of a new and liberal commander in chief as he tries to sell...