The war began March 19, 2003, with an overwhelming show of American military might, described by the unforgettable phrase “shock and awe.” Within weeks, the United States achieved the primary objective of Operation Iraqi Freedom, as the military operation was called, ousting the regime of dictator Saddam Hussein. Yet the military campaign that began so auspiciously ended up deeply dividing Americans and alienating key U.S. allies. As Americans looked back on the war four years ago, 62% said it was not worth fighting. … In a pivotal moment in the Iraq debate, Powell presented what he described as “facts and...