In 1800, the population of the U.S. was five million, but it was about to explode. By 1820 it had doubled. The population was not only growing, but moving: in 1820, eight million Americans lived east of the Appalachians; by 1860 the population was more than thirty million, but half...

"We are in the midst of the most terrible battle of the war—perhaps history." 1 So wrote General George McClellan to Chief of Staff Henry Halleck and President Abraham Lincoln before the telegraph wires went dead the morning of September 17, 1862. The wires would remain dead all day, as...