France had made preparations for invasion on her eastern frontier. A series of strong forts, according to prevailing ideas of military science, had been erected from the Swiss border to Longwy, at the southern bounds of Belgium. It comprised the fortresses of Belfort, Epinal, Toul, Verdun and Longwy, with many outlying forts and batteu positions. A fortress, in the sense here used, is a str.ong central position with outlying forts at a distance of from four to eight miles, so placed that their guns can cover most of the intervals between the forts themselves. In these intervals trenches were constructed to be held against infantry attacks. The forts were generally made of strong con crete walls and contained cannon whose range was about six miles. Between the great for tresses along this line, 150 miles long, were many smaller forts and well-defended ridges, so that the French had a right to feel that their eastern border was well defended.
But north of Longvvy the line of defense was weaker. Here began the border of Bel gitun, which France had long believed would protect her against Germany. It is true that there were many indications that Germany would not respect Belgian territory nor the neutrality of Luxemburg, the southwest comer of which touched France on a border of 15 miles, just east of Longwy. She expected that fortress to give her security in this quarter, if Germany, violating international law, massed troops in that neutral duchy. As to Belgium, it was believed that its people would resist a German attack until the French could send help, but if that failed there was a fortified lint just southwest of the Belgian frontier in which were the fortified towns of Lille, Maubeuge and Mezieres, the second being very strong. The line connected with the Longwy area along the high ground northeast of the Meuse, but west of Lille it was in the air. It was not a strong line, but the French thought it would derive additional strength by the support of the Belgian fortresses of Liege and Namur.
In considering possible lines of defense the French High Command had to choose between looking for the enemy either along the eastern border or through Belgium. They considered the former the more probable, and their best efforts of defense were spent there. Probabry for this reason the Germans chose the latter as the surest way to finish France in a quick blow; for they could never hope to penetrate the eastern line of fortresses in the six weeks during which they expected to crush their west ern foe.
Now the Belgian area of operations is like this: Draw a straight line on the map from Longwy to the Dutch border on the north and the distance is 90 miles. For the first 70 miles from Longwy the line crosses two broken, forest-clad and rather thinly. populated regions, the southern Ardennes and the wooded valley of the Meuse, the northern border of the latter being the Meuse River from Namur to Lie.ge, where it turns northward to the Dutch border by way of Maestricht. This wooded region is not favorable for manceuvring large armies, although the Germans proved that it was pos sible to send them through its roads in order to concentrate heavy forces in the region be yond. North of this wooded region lies the Belgian plain, thickly populated in 1914 and devoted to many kinds of industry in which lived a body of slcilled workers. North of the Meuse Valley this plain runs in a narrow neck, 20 miles wide, as far east as the German boiler near Aix-la-Chapelle. It is crossed by the Meuse north of Liege, and the river, if well fortified, would make a good line of defense. The BelFians, however, had done much to de fend Liege, but they did nothing to hold the river bank. Thus It was possible for an in vading army that was in superior force to cross the river out of reach of the guns of Liege, sweep around the town, and take it by siege operations. The Germans, when they had de cided to attack through Belgium, proposed to enter Belgium through this gateway, mass their troops in the plain, sweep around to the west of Namur until the place was either talcen or masked, and then pour down past Lille, Pe ronne and Ainiens to the vicinity of Paris. If the French tried to hold Maubettge, or the country south of it, the superior German army would encircle them from the west and repeat the tactics by which great French artnies were captured in 1870 at Sedan 'and Metz.
The plan of the Frenth High Command was as follows: It would concentrate the best troops on the eastern front. If the Germans met them there great battles on equal footing would follow. The French wanted nothing better than to meet the foe as equals. If, how ever, the Germans came through Belgium they would be checked by the Belgians, who, rein forced by troops from France, would hold back the German advance at Liege, Namur and Maubeuge, while the main French forces would break through the German defenses into Alsace and Lorraine, seize the Rhine nnd produce con sternation in Germany itself. We shall see what befell this plan.