This road stretches from the seat of the war at Belgrade on the Danube down a narrow valley, the Morava, thence through the highlands of Macedonia into the Vardar Valley to Saloniki, on the AEgean Sea. At Nish, above Macedonia, another road branches off into Bulgaria across the plains of Thrace and into Constantinople. This was the road by which the Crusaders swarmed down to conquer the Holy Land. This was the road by which, hundreds of years later, the Moslems swarmed up into the plains of Hungary and overran the south of Europe, until they were finally checked outside the gates of Vienna. Nothing is more significant of the terror that these marching hosts inspired than the fact that, with the exception of a few larger towns, the villages hid themselves away from this highway in the hills. Bear clearly in mind that in the existence of this narrow way to the Orient lies the key not only to the causes of the war, but to the military campaigns that we shall follow in this region. For it is the Teutons who would in the Great War, like the Crusaders of old, pass down this highway and again conquer the East, though in this case their object is trade, and not the Holy Sepulcher. To secure the pathway through this strategic country it also is necessary to have control of the territory on all sides, and this is quite as true in a political as in a military sense. To secure their pathway up into Europe the Turks once conquered all the peoples in the Balkans, except those inhabiting the mountains over on the Adriatic: the Montenegrins and a small city called Ragusa, just above Montenegro in Dalmatia. It is not at all peculiar that just here, in almost the same locality, the Teutons should meet with the first and strongest resistance. A study of the territory in which the first fighting of the war occurred will explain the foregoing calculations. It will be observed that Austrian territory runs down past the eastward turn in the Danube, along the frontier of Montenegro, until it narrows gradually into a tip at Cattaro, just below Cettinje, the Montenegrin capital. This land is composed of the three provinces of Bosnia, Herzegovina and Dalmatia. All this territory is inhabited by the same race that peoples Serbia and Montenegro--the Serbs. In fact, the Slavic population reaches up all along the coast to Trieste, and even a little beyond. For this reason it is in this direction that we shall see the Serbians and the Montenegrins invade Austrian territory, after their initial success in repulsing the Austrian invasion.