French air scouts brought in correct information that they had seen the armies of the Duke of Wuerttemberg and crown prince massed along the southern Luxemburg and Belgian forest region. But under the foliage there was another army unseen--that of General von Hausen. The French moved their Fifth Army up to position on the line of the Sambre. They advanced their Third Army, commanded by General Ruffey, upon Luxemburg, and their Fourth Army under General de Langle de Cary across the River Semois to watch the Meuse left bank and gain touch with General Lanzerac. General de Cary came from Sedan, throwing out detachments upon the Meuse left bank. These operations were to confront the armies of the Duke of Wuerttemberg and crown prince. But the French apparently knew nothing of the movements of the army of General von Hausen. Their air scouts either could not distinguish it from the armies of the Duke of Wuerttemberg and the crown prince, amid the forest of the Ardennes, or they did not observe it at all. To the army of General von Hausen there clings a good deal of mystery. When last noted by us, previous to the minor battle of Dinant, it had been formed by forces drawn from the armies of the Duke of Wuerttemberg and crown prince. Ostensibly at that time, it was destined to support, as a separate field force, the armies of Von Kluck and Von Buelow. Possibly the Germans had begun to doubt how long Liege could hold out. Von Kluck was compelled to mark time in his impetuous march on Central Belgium. His losses had been heavy. Support in strength seemed urgent. But this need passed as the Liege forts fell one after the other under the fire of the German siege guns. General von Hausen was released for action elsewhere. Thus we may assume, he was ordered to follow the armies of the Duke of Wuerttemberg and crown prince down through the Ardennes to strike the Meuse south of Namur. By this time he had been substantially reenforced. Now under his command were the complete Twelfth and Nineteenth Corps, and the Eleventh Reserve Corps. Also a cavalry division of the Prussian Guard, with some other detachments of cavalry. His Eleventh Reserve Corps were Hessians, the Twelfth and Nineteenth Corps were Saxons. The latter two corps were regarded as among the best in the German army. In the Franco-Prussian War they fought with conspicuous bravery through every battle in which they were engaged. They won the battle for Prussia at Gravelotte by turning the French right and capturing St. Privat. They marched to Sedan under the crown prince--subsequently the Emperor Frederick--to occupy the first line in the hard fighting of the Givonne Valley. During the siege of Paris they occupied a part of the German northern line, finally to march in triumph into Paris. This infantry and cavalry of the Prussian Guard stiffened Von Hausen's force into an army of battle strength.