Jonathan Letterman was an outpost medical officer serving in Indian country in the years before the Civil War, responsible for the care of just hundreds of men. But when he was appointed the chief medical officer of the Army of the Potomac, he revolutionized combat medicine over the course of four major battles -- Antietam, Fredericksburg, Chancellorsville and Gettysburg -- that produced unprecedented numbers of casualties. He made battlefield survival possible by creating the first organized ambulance corps and a more effective field hospital system. He imposed medical professionalism on the chaos of battle. Confronting conditions of squalor, poor nutrition, and rampant disease that left 20 percent of hte men unfit to fight, he improved health and combat readiness by pioneering hygiene and diet standards...His principles of battlefield care continue to be taught to military commanders and first responders.

Introduction: "We are almost worked to death" -- Not a learned profession: "Open-hearted frankness" -- Outpost medicine: "We had no bandages" -- The Hammond alliance: "Their wounds, as yet, undressed" -- Taking medical command: "I found it in a deplorable condition" -- Antietam: "I pray God may stop such infernal work" -- Fredericksburg: "A huge serpent of blue and steel" -- Chancellorsville: "What will the country say?" -- Gettysburg: "I turned away and cried" -- Validation: "Little more remained to be done" -- Wildcatter: "A good kind husband" -- Compassionate coroner: "I have done my duty faithfully" -- Enduring legacy: "War is a terrible thing at best" -- Epilogue: "Today I am used up.".