The present volume--No. 3 of the series: “The Americans in the Great War”--see Volumes 1 (“The Second Battle of the Marne”) and 2 (“The Battles of St. Mihiel”)--deals with the Argonne proper and with the Marshes of the Argonne, that is to say, the greater part of the country lying between the Battlefields of Champagne and Verdun, described in the Michelin Guides: “The Battles of Champagne” and “Verdun.” The Argonne was never independent, administratively or politically. It has always been attached to a neighbouring State, large or small. Originally a border-land between Champagne and Lorraine, it belonged formerly to the three Bishoprics of Châlons, Rheims, and Verdun. Later it became the Comté of Argonne, with Sainte-Menehould as capital, but remained tributary to the three bishoprics. After the annexation of Champagne, the King of France and the Duke of Lorraine each took that part of the Argonne bordering on his territory. Later it was divided between the Province of Champagne, the Duchy of Bar, and the Duchy of Lorraine. With the exception of several lateral valleys which divide it into sections difficult of access to one another, the Argonne, covered with thick forests, and for long roadless, presented an all but insuperable obstacle to military operations. These valleys, or defiles, considered from north to south, are: the passes of Chesne Populeux, Croix-aux-Bois, Grandpré, Chalade, and Les Islettes. These five passes, famous since the campaign of 1792, which ended in the French victory of Valmy, have often been disputed. [Illustration: THE DEFILES OF THE ARGONNE] The Argonne Campaign of 1792 At the end of August, 1792, General Dumouriez--in face of the rapid advance of the Prussians, who were besieging Verdun, and of the Austrians, who were drawing near Stenay--was forced to abandon his proposed offensive in Belgium, and continue on the defensive. Divining the intentions of the enemy to reach first the Aisne and then Châlons, in order to march on Paris, he decided to block the roads from Lorraine into Champagne by a defence of the Argonne. On September 1, he marched from Sedan on Grandpré, whence on the 3rd he despatched a detachment against St. Juvin. With his right resting on the Plateau de Marcq, his left on Grandpré, and his artillery parked at Senuc, he took up his headquarters at the Château of Grandpré, the property of one of his friends, Semonville. His lieutenant, Dillon, occupied Les Islettes and the course of the Biesme as far as Passavant-en-Argonne, with headquarters at Grange-aux-Bois. General Kellermann was marching to join Dumouriez, and arrived by the Toul-Bar road. At the call of Dumouriez, the inhabitants of the districts of Clermont and Bar retired to the forests of the Argonne with all the provisions and supplies which they could carry with them.