On the morning of Friday, the 29th of July, the forward movement of the French army will have commenced. In which direction? A glance at the map will show it. The valley of the Rhine, on the left bank, is closed in to the west by the mountain chain of the Vosges from Belfort to Kaiserslautern. North of this latter town the hills become more undulating, until they gradually merge in the plain near Mayence. The valley of the Moselle in Rhenish Prussia forms a deep and winding clough, which the river has worked out for itself through a plateau, which rises to the south of the valley into a considerable range called the Hochwald. As this range approaches the Rhine the plateau character becomes more predominant, until the last outlying hills meet the farthest spurs of the Vosges. Neither the Vosges nor the Hochwald are absolutely impracticable for an army; both are crossed by several good high-roads, but neither are of that class of ground where armies of from 200,000 to 300,000 men could operate with advantage. The country between the two, however, forms a kind of broad gap, twenty-five to thirty miles in width, undulated ground, traversed by numerous roads in all directions, and offering every facility to the movements of large armies. Moreover, the road from Metz to Mayence goes through this gap, and Mayence is the first important point on which the French will probably move. Here, then, we have the line of operations prescribed by nature. In case of a German invasion of France, both armies being prepared, the first great encounter must take place in the corner of Lorraine east of the Moselle and north of the railway from Nancy to Strasbourg; so, with a French army advancing from the positions where it concentrated last week, the first important action will take place somewhere in this gap, or beyond it, under the walls of Mayence. The French army was thus concentrated: Three corps (the 3rd, 4th, and 5th) in a first line at Thionville, St. Avold, and Bitche; two corps (the 1st and 2nd) in second line at Strasbourg and Metz; and as a reserve, the Guards at Nancy and the 6th Corps at Ch lons. During the last few days the second line was brought forward into the intervals of the first, the Guard was moved to Metz, Strasbourg was abandoned to the Mobile Guard. Thus the whole body of the French forces was concentrated between Thionville and Bitche, that is, facing the entrance of the gap between the mountains. The natural conclusion from these premisses is that they intend marching into it. Thus, the invasion will have commenced by occupying the passages of the Saar and the Blies; the next day s proceedings will probably be to occupy the line from Tholey to Homburg; then the line from Birkenfeld to Landstuhl or Oberstein to Kaiserslautern, and so forth that is to say, unless they are interrupted by an advance of the Germans. There will be, no doubt, flanking corps of both parties in the hills, and they, too, will come to blows; but for the real battle we must look to the ground just described. Of the positions of the Germans we know nothing. We suppose, however, that their ground of concentration, if they intend to meet the enemy on the left bank of the Rhine, will be immediately in front of Mayence, that is, at the other end of the gap. If not, they will remain on the right bank, from Bingen to Mannheim, concentrating either above or below Mayence as circumstances may require. As to Mayence, which in its old shape was open to bombardment by rifled artillery, the erection of a new line of detached forts, 4,000 to 5,000 yards from the ramparts of the town, seems to have made it pretty secure. Everything points to the supposition that the Germans will be ready and willing to advance not more than two or three days later than the French. In that case it will be a battle like Solferino two armies deployed on their full front, marching to meet each other. Much learned and over-skilful manoeuvring is not to be expected. With armies of such magnitude there is trouble enough to make them move simply to the front according to the preconcerted plan. Whichever side attempts dangerous manoeuvres may find itself crushed by the plain forward movement of the masses of the enemy long before these manoeuvres can be developed. A military work on the Rhine fortresses, by Herr von Widdern, is much talked of just now at Berlin. The author says that the Rhine from B le to the Murg is not fortified at all, and that the only defence of South Germany and Austria against a French attack in that direction is the strong fortress of Ulm, occupied since 1866 by a mixed force of Bavarians and W rttembergers, amounting to 10,000 men. This force could in case of war be augmented to 25,000 men, and 25,000 more could be stationed in an entrenched camp within the walls of the fortress. Rastatt, which, it is expected, will present a formidable obstacle to the French advance, lies in a valley through which runs the river Murg. The defences of the town consist of three large forts, which command the surrounding country, and are united by walls. The southern and western forts, called Leopold and Frederick, are on the left bank of the Murg; the northern fort, called Louis, on the right bank, where there is also an entrenched camp capable of holding 25,000 men. Rastatt is four miles from the Rhine, and the intervening country is covered with woods, so that the fortress could not prevent an army from crossing at that point. The next fortress is Landau, which formerly consisted of three forts one to the south, one to the east, and one to the north-west, separated from the town by marshes on the banks of the little river Queich. The southern and eastern forts have been recently abandoned, and the only one kept in a state of defence is now the north-western. The most important and the best situated fortress in this district is Germersheim, on the banks of the Rhine. It commands a considerable stretch of the river on both sides, and practically closes it to an enemy as far as Mayence and Coblenz. It would greatly facilitate the advance of troops into the Rhine Palatinate, as two or three bridges might be thrown across the river, besides the floating bridge which already exists there, under cover of its guns. It would also form a basis of operations for the left wing of an army posted on the line of the River Queich. Mayence, one of the most important of the Rhine fortresses, is commanded by some of the adjoining hills; this has rendered it necessary to multiply the fortifications in the town, and there is, in consequence, hardly room enough for a large garrison. The whole of the country between Mayence and Bingen is now strongly fortified, and between it and the mouth of the Main (on the opposite bank of the Rhine) there are three large entrenched camps. As to Coblenz, Herr von Widdern says that it would require a force six times as large as the garrison to besiege it with any prospect of success. An enemy would probably begin the attack by opening fire on Fort Alexander from the hill known as the Kuhkopf, where his troops would be sheltered by the woods. The author also describes the fortifications of Cologne and Wesel, but adds nothing to what is already known on the subject.
Notes on the War. Engels 1870-71