Originally the fortress of Dvinsk was far from being up to date or particularly effective and imposing. It consisted of an old citadel which, it is true, had been improved considerably; but even then its outworks extended hardly farther than a mile beyond its own range. As soon as General Russky assumed command he began feverishly to improve these conditions. In this undertaking he was greatly assisted by the nature of the countryside surrounding Dvinsk. Immediately to the northwest, west, south, and southeast the River Dvina formed a strong line of natural defense. Beyond that was a region thickly covered with small and big lakes, which swung around Dvinsk as a center, in the form of an immense three-quarters circle, starting to the south of the Libau-Ponevesh-Dvinsk railroad and stopping just west of the Dvinsk-Pskoff-Petrograd railroad. The diameter of this circle varies from thirty miles to sixty. The ground between these lakes is swampy in many places, difficult of approach, and comparatively easy to defend even against superior forces, especially because most of it is not entirely flat, but interspersed with hills and woodlands. Throughout this entire district the Russians built a dense network of trenches, and it was especially by means of these that the Germans were repulsed not only successfully but with great losses to their attacking forces. The more important of these earth fortifications were built in a novel fashion. The main part of each had the form of a crescent with its horns turned toward the enemy. Every attack from the latter, in order to find a point big enough for an effective attack, had to be frontal in nature; that means, it had to be directed against the main part of the crescent-shaped trench. But, whenever such a frontal attack would be executed and just as soon as the attackers would be inside of the sides of the crescent, machine guns and rifle fire from its two horns would hit them on both flanks and frequently destroy them utterly. In order to make the Germans advance far enough into the crescent, advanced trenches had been built in front of its horns, which were connected with the main part of the crescent by communicating trenches.