Book excerpt: General Winfield Scott Hancock was perhaps the most influential officer in the federal lines, though he commanded only one of seven Union corps at Gettysburg. On day one, he rallied fleeing troops and placed them in the formidable position the Union army occupied for the remainder of the battle. In a frantic few minutes on day two, he masterfully conducted reinforcements into a yawning gap in his defensive line, securing the position just moments before the Confederates advanced to try to take it. On the third day, he led the successful defense against the massive frontal assault known as Pickett's Charge. Understanding Hancock's pivotal actions at Gettysburg is essential to understanding the battle itself. This book covers his entire life and military career.