The fourth part of the plan was the holding fast to the point of Verdun, for thereby the communication of the armies of the Central Powers was seriously weakened. It is to be remembered that this actual fighting army of more than a million men depended for food and for ammunition supplies upon the routes from Belgium and Luxemburg by way of Mezieres and Montmedy, and the circuitous line to Brussels via St. Quentin. Had Maubeuge fallen a little earlier the situation of the Central Powers would have been less difficult, and both commissariat and ammunition problems would have been easier of solution. But Maubeuge held out until September 7, 1914, and by that time the prime results of the battles of the Marne had been achieved. To this problem Verdun was the key, for from Metz through Verdun ran the main line, less than one-half the length of line to the Belgian bases of supplies, and, owing to the nature of the country, a line that could be held with a quarter the number of men. But Verdun stood, and General Joffre held the two armies back to back, converging on the point at Verdun. Such was the country over which the battles of the Marne were fought, such were the numbers and dispositions of the several armies on each side, and such, as far as can be judged, were the plans and counterplans of the strategic leaders in the great conflict. CHAPTER XIV FIRST MOVES IN THE BATTLE The first movement in this concerted plan was taken by the German extreme right. This was the closing in of General von Kluck's army in a southeasterly direction. It was a hazardous move, for it required General von Kluck to execute a flank march diagonally across the front of the Sixth French Army and the British Expeditionary Force. At this time, according to the dispatches from Sir John French, the British army lay south of the Marne between Lagny and Signy-Signets, defending the passage of the river and blowing up the bridges before General von Kluck. On September 4, 1914, air reconnaissances showed that General von Kluck had stopped his southward advance upon Paris, and that his columns were moving in a southeasterly direction east of a line drawn through Nanteuil and Lizy on the Ourcq. Meanwhile the French and British generals more effectually concealed their armies in the forests, doing so with such skill that their movements were unmarked by the German air scouts. All that day General von Kluck moved his forces, leaving his heavy artillery with about 100,000 men on the steep eastern bank of the Ourcq and taking 150,000 troops south across the Marne toward La Ferte Gaucher. He crossed the Petit Morin and the Grand Morin, all unconscious that scores of field glasses were trained upon his troops.