But henceforward the French right stood like a rock in front of Nancy under General de Castelnau, and at the Trouée des Charmes under General Dubail, and the Germans sustained a series of bloody checks. Meanwhile the French left and centre by retreating for five marches extended the pursuing Germans to the utmost while falling back themselves on their own reserves and supplies. And by September 6 (the 37th day) the French armies turned and assumed the offensive on the whole front of 120 miles from Paris to Verdun. In addition a new French army under General Maunoury had come into existence to the north of Paris which attacked the German right, and all the time the resistance of the Nancy army (de Castelnau) and of the army of General Dubail on its right continued unbreakable. Thus from September 6 the whole of the French and German armies and the British Expeditionary Force were locked in general battle on a front of over 180 miles, with practically every division and all their reserves on both sides thrown in. This battle, which lasted for four days, was the greatest of the war. The Germans aimed not at the capture of Paris or Verdun or Nancy, but at the final destruction of the French military power. Had they succeeded in breaking the French front between Paris and Verdun or in falling upon its rear from the direction of Nancy, nearly half the French Army, certainly more than a million men, would have been cut off in the Verdun angle. The rest, whatever happened in the neighbourhood of Paris, would have had to retreat to the southward and would never again have been numerous enough to form a complete front. Compared with stakes like these, the entry into Paris by the German right flank or the capture of the Channel Ports by a couple of German corps were insignificant and rightly discarded by the German Headquarters. Once the French Army was cut in half and finally beaten, everything would fall into their hands. They therefore directed all their available troops to the battlefield, ignored the Channel Ports, and compelled von Kluck, commanding their right army, to skirt Paris and close in to their main battle front. How near they were to success will long be debated and never decided. But certainly they were within an ace. No military reproach lies upon their disregard of other objectives: but only upon any failure to disregard them. It is not to their neglect to enter Paris or seize Calais that their fatal defeat was due, but rather to the withdrawal of two German army corps to repel the Russian invasion of East Prussia.