Topography of the Theatre of Operations.—Bohemia, where the main campaign was fought, is, generally, a country of open rolling plains, highly cultivated. Except the rivers, there are few obstacles to the movements of troops of all arms. But on the northern marches, between Bohemia and Prussia, lies a crescent of mountains, from 2,000 to 4,000f t. in height. These mountains are known in the east, on the Silesian frontier, as the Sudeten Gebirge, in the centre as the Riesen Gebirge, and in the west, on the Saxon frontier, as the Erz Gebirge. The Riesen Gebirge are the most formidable. They constituted a definite bar rier, some 36m. in length and 20 in depth, to the movement of large forces. The principal routes from Prussia into Bohemia passed round either end of the Riesen Gebirge, through the lower and less rugged Sudeten and Erz Gebirge,—a fact which had, as will be seen, an important bearing on Prussian strategy. The Sudeten and Erz Gebirge were not steep, troops of all arms could move freely off the roads (except where the country was thickly wooded) and the so-called "passes" were in no sense defiles such as those in the Alps or on the north-west frontier of India. Of the rivers, the Elbe, which rises in the Riesen Gebirge and eventually leaves Bohemia through the Erz Gebirge, is a considerable obstacle, 6o to 7o yards broad at Koniggratz. The Iser, too, is deep, swift and broad, and had some strategical and tactical significance. The other streams in the theatre of opera tions were unimportant, except the Bistritz, as will be seen, at the battle of Sadowa.
Mobilization and Concentration.—After a long period of diplomatic negotiation, during which both sides had made cer tain military preparations, Austria ordered the mobilization of her Army of the North on April 27. Prussia followed suit a week later. Mobilization arrangements had not then reached the nicety of timing that in 1914 made a delay of even a few hours dangerous and thus rendered the mobilization of a European state practically equivalent to a declaration of war. The Prussian Corps were originally concentrated in their recruiting areas, a waste of time, since they had again to be broken up for the movement to the frontier by rail, which began on May 16 and was completed by June 5 (the most considerable use of railways in war up to that time).
Much ink has been spilt in criticism and defence of von Moltke's strategical deployment of the Prussian forces for this campaign, of which space permits only the barest possible out line here. The outstanding features of a strategical problem, which von Moltke had been studying in all its bearings for six years, were firstly, the mountain belt, with the almost roadless Riesen Gebirge in the centre, which had to be crossed if an offen sive campaign into Bohemia were contemplated, and secondly, the salient formed by the province of Silesia, which greatly compli cated the problem of defence should the enemy obtain the initia tive. Von Moltke believed that Prussia's better transport arrange ments would enable her armies, in spite of their later mobilization, to forestall the Austrians in northern Bohemia, provided they were moved thither with all speed, passing through the mountains on a broad front. Thus the importance of time, which impelled
him to use all available railways, motived the original detrainment on a front of 275 miles, from Halle to Neisse. Thence the corps were moved inwards, and by June 8 stood in three groups on a front of about r so miles : Army of the Elbe (VIII. Corps, i4th Div.) centre about Torgau; I. Army (II., III., IV. Corps) under Prince Frederick Charles, Senftenburg to Gorlitz; II. Army (I., V., VI. Corps) under the Crown Prince, centre about Landshut; the Guard Corps was still at Berlin. Von Moltke would now have liked to unite the armies by a movement into Bohemia. But there followed a delay of nearly a fortnight due to the reluctance of King William to appear the aggressor in the con flict. This delay was almost fatal to the Prussian plan.
Meanwhile the Austrian army had concentrated round Olmiitz in Moravia, near the Silesian frontier, with a detachment of the I. Corps and a cavalry division in northern Bohemia. The Crown Prince, the commander of the Prussian II. Army, convinced that an Austrian invasion of Silesia was imminent, proposed to move his army eastwards to about Neisse, to meet the danger, and also requested the strengthening of his army by the Guard Corps, originally allotted to the I. Army. Moltke was somewhat reluc tantly compelled to agree to a move that still further separated the II. Army from the I. and exposed it to the danger of having to meet, unsupported, an attack by the Austrian main forces. This extension of front, for which von Moltke has been criti cized, was probably less dangerous than it appeared. Von Moltke was sure of the tactical superiority of the Prussian infantry, with its breech-loading weapon, and could therefore count on the ability of the II. Army to delay any Austrian invasion long enough for the I. Army to intervene ; he was also probably aware of the predilection of the Austrian high command for defensive strategy.
On June 15 King William relieved von Moltke of some of his anxieties by sanctioning the invasion of Saxony by the Army of the Elbe. Dresden was occupied on June 19 without fighting, the Saxon Army retiring into Bohemia. This brought the Army of the Elbe into close touch with the I. Army and it was now placed under the command of Prince Frederick Charles. There was still a wide gap between the I. and II. Armies, and a forward concen tration in Bohemia was now hazardous, since Benedek had on June 17 ordered the march of the whole Austrian army from Olmiitz towards Josefstadt. Nevertheless, Moltke chose the bold part, and on June 2 2 issued his famous order for the advance of the I. and II. Armies towards a point of junction at Gitschin. The forces of both combatants were thus hurrying towards the same area—the Austrians united, the Prussians seeking to unite.