This volume, the second to be published, covers the outbreak of war in July–August 1914, the German invasion of Belgium, the Battles of the Frontiers, and the pursuit to the Marne in early September 1914. The first month of war was a critical period for the German army and, as the official history makes clear, the German war plan was a gamble that seemed to present the only solution to the riddle of the two-front war. But as the Moltke-Schlieffen Plan was gradually jettisoned through a combination of intentional command decisions and confused communications, Germany’s hopes for a quick and victorious campaign evaporated.