The position of the Allied armies was based on the resisting power of Namur. It was expected that Namur would delay the German advance as long as Liege had done. Then the French line of frontier fortresses--Lille, with its half-finished defenses; Maubeuge, with strong forts and a large garrison; and other strongholds--would form a still more useful system of fortified points for the Allies. The German staff, however, had other plans. At Liege they had rashly endeavored to storm a strong fortress by a massed infantry attack, which had failed disastrously until their new Krupp siege guns had been brought up. These quickly demolished the defenses. These siege guns, therefore, which had thus fully demonstrated their value against fortifications soon brought about the total defeat of the French offensive, and compelled the Allies to retreat from Belgium and northern France. The Germans lost no time in investing Namur, and on Saturday, as noted above, August 22, 1914, the fortress fell into the invaders' hands. On the same day, August 22, 1914, the Fifth French Army, under the lead of General Lanrezac, was enduring the double stress of Von Buelow's army thundering against its front, and Von Hausen's two army corps pressing hard upon its right flank and rear, threatening its line of retreat. Against such terrific odds the French line at Dinant and Givet broke, exposing the flank and rear of the whole army; and by the evening of that day, August 22, the passages of the River Sambre, near Charleroi, had been forced, and the Fifth Army was falling back, contesting every mile of the ground with desperate rear-guard action. The British, meanwhile, defending the Mons position, were in grave danger of being cut off, enveloped, and destroyed. Sir John French had put his two army corps into battle array. He had about thirty miles of front to defend, with Mons nearly in the center. On Sunday afternoon, August 23, 1914, the full weight of the German onset fell for the first time upon the British. All that night the British were under the fire of German artillery. Sir John French realized the danger of his Maubeuge-Jenlain position, and on Monday evening, August 23, 1914, realizing the importance of putting a substantial barrier, such as the Somme or the Oise, between his force and the enemy, gave orders for the retirement to be continued at five o'clock the next morning, August 24, 1914. He had decided upon a new position about the town of Le Cateau, east of Cambrai. Before dawn, August 25, 1914, the southward march over rough, hilly country was resumed, and toward evening of August 25, 1914, after a long, hard day's fighting march over the highroads, in midsummer heat and thundershowers, the Guards Brigade and other regiments of the Second Corps, wet and weary, arrived at the little market town of Landrecies. From Landrecies, after an encounter with a German column, they marched south toward Wassigny on Guise.