Book excerpt: Abraham Lincoln was the first president whose time in office was captured by photography. Lincoln was able to use the camera to shape his image as a man of the people, and Americans responded by electing him during the turbulent times leading up to the Civil War. Inspired by a glass photographic negative recently discovered in the National Archives' Civil War collection that is the only confirmed existing picture of Lincoln before his historic Gettysburg Address, Sandler tells the story behind the photos that document Lincoln's rise from frontiersman to chief executive.