Colin Powell, who in four decades of public service helped shape U.S. national security, died on Monday. He was 84. Despite a stellar career, Mr. Powell had expressed a fear that he would be remembered for a single event: his role in leading his country to war in Iraq. We look back on the achievements and setbacks of a trailblazing life. Guest: Robert Draper, writer for The New York Times Magazine and author of “To Start a War: How the Bush Administration Took America into Iraq.”