In Operation Cobra, six US divisions during six dramatic days in Normandy ended the stalemate on the western front, breaking through German defenses after seven weeks of grueling attrition warfare. After D-Day examines the experiences of U.S. soldiers in the July 25-30, 1944, Normandy campaign: their mistakes, hardships, and fears, as well as their leadership, courage, and determination. Drawing on original archival sources, Carafano argues that previous accounts of Operation Cobra are flawed. Standard explanations of its success--the force of air power, innovative tactics, superior logistics, the inestimable value of "citizen soldiers," hedgerow busting "rhino" tanks--are in fact myths. And serious mistakes were made: one of the most famous US generals, Omar Bradley, ordered strategic bombing close to US lines, a decision that led to the killing and maiming of hundreds of US soldiers by "friendly fire." Nonetheless, Carafano demonstrates, operational flexibility--the ability of commanders to exercise effective combat leadership and take advantage of troop strengths and material advantages--resulted in Allied victory.