When the blow fell at last there were several reasons which justified General Joffre in using them for purposes of offence instead of in the _rôle_ which French and Germans alike expected of them. Being a soldier and not a politician, he realized that he could not afford to wait and see. It was a clear gain that his action should be the exact opposite of what the Germans looked for. They were so overwhelmingly sure of their military superiority that they practically counted on a walk-over. Besides Verdun, other towns far behind the line of the frontier fortresses, such as Besançon and Dijon, were the appointed rendezvous at an early date in August of the German soldiers who could not be ready to join the colours at the outset, and even the officials who were to have governed these towns after their expected conquest had received their commissions well in advance of the declaration of war. The Kaiser and his advisers had made the common mistake of despising the enemy they were sent to attack. Both in _morale_ and in men the armies of the east proved far stronger than they had expected. The consequent upsetting of their original plan of campaign was in itself a strong vindication of General Joffre’s policy. But he had another object in view. The first point was to have enough troops on the eastern frontier to prevent the Germans from breaking through the line of fortresses. The second—no less important, once the march through Belgium had begun—was to keep a large part of the enemy’s forces busily employed at a distance from the northern theatre of operations. That was the reason and the justification of the offensive in Alsace and Lorraine. Up to a point this forward movement of the French was successful. From Metz the frontier runs south-east for about sixty miles, up the valley of the river Seille, to the Donon, a mountain just over 3000 feet high at the north end of the Basses Vosges, and from there, a trifle west of south along the crests of the range and across the Trouée of Belfort for about the same distance to Pfetterhausen on the Swiss frontier. The Vosges half of this line, practically parallel with the course of the Rhine, is divided into three sections, from the Donon to the Climont (12 miles), from the Climont to the Col de Schlucht (20 miles), and from the Col de Schlucht to the Ballon d’Alsace (18 miles). In the northern section the range is broken by the valley of the Bruche, commanded from the north by the Donon, which runs from south-west to north-east past Saales and Schirmeck towards Strassburg. In the central section, steep on the French side, but on the east sloping gently down to the valley of the Ill, the chief passes are Ste. Marie aux Mines and the Col du Bonhomme, with a narrow wooded crest seven miles long at an average altitude of 3000 feet between them.