The second part of the frontier is the ramparts of the Dolomite and Carnic ranges through which an important offensive was possible for neither belligerent. The main pass, at Ampezzo, 5,000 feet high, makes a sharp detour toward the west to circumvent the mass of Cristallo, and here the road is a narrow defile commanded by a hundred points of danger. The adjacent passes of Misurina and the Monte Croce are no better, and the defiles to the east contain little more than bridle paths. The lowest pass, which leads from the valley of the Fella by Pontebba to the upper streams of the Drave and carries the railway from Venice to Vienna is only 2,615 feet high at its greatest elevation. Although this is the easiest of the great routes through the mountain barrier, it is still narrow and difficult. A modern army given the advantages of time and preparation should be able to close and hold it with ease. Although the maps show few natural difficulties on the third section of the frontier to compare with those farther west, it is not the obvious avenue of attack a hasty survey would seem to suggest. It is only twenty miles wide and behind it is the line of the River Isonzo with hills along its eastern bank. The upper part of this stream, above Salcana, is a ravine; then comes six miles of comparatively level ground in front of Gorizia; then the hills begin again and sweep round to the seacoast by Monfalcone. What this front lacks in natural defenses had been amply supplied before the war opened by Austria with artillery and men. Toward this narrow twenty-mile stretch, and especially toward the plain before Gorizia, tended, in a sense, however, all the operations of the Italian strategists. The engagements fought during the first of the Italo-Austrian struggle all had their bearing upon the great offensive launched later against Gorizia. But the natural lay of the land was by no means the only consideration with which the rival generals had to deal. In respect to lateral communications Italy had the advantage. Behind her invading armies stretched an elaborate system of railways through her northern provinces. Austria had a railway running through the whole curve of the frontier, but owing to the difficulty of breaking through from the hill valleys this system had few feeders. This lack of branch lines meant that Austria had to concentrate any offensive at certain definite places--Trent, Tarvis, and Gorizia. Italy aimed at these points and one more, Franzensfeste, the junction of the Pusterthal line with the railway from Innsbruck to Trent. If she could take this point she could cut Austria's communications in the whole Trentino salient. But Franzensfeste was the most difficult of any of these local points for Italy to reach, for south and east of it lay the bristling system of the Dolomites.