Geographically speaking, the Balkan nations are those situated in the big peninsula of southern Europe which lies below the Danube River and the northern border of Montenegro.  Some authorities, however, include Rumania, and others even bring in Austria’s Slavic provinces, Bosnia and Herzegovina.

The most noticeable feature of this vast war-ridden region is its mountains.  Those same Carpathian Mountains, which form the natural boundary between the land of the Magyars and the Russian plains, take a sudden turn westward at the Rumanian frontier, then sweep around in a great semicircle, forming a shape resembling a scythe, the handle of which reaches up into Poland, the blade curling around within the Balkan Peninsula.  Behind the handle, and above the upper part of the blade, stretch the broad plains of Hungary, through which flows the great Danube, the largest river in Europe next to the Russian Volga—­a river which flowed with blood during the Great War.  Just in the middle of the back of the blade this great river bursts through the mountain chain, swirling through the famous Iron Gate into the great basin within the curved blade.  On the south of its farther course to the Black Sea lie the plains of northern Bulgaria.

The curving chain of mountains below the Iron Gate is the Balkan Range.  But excepting for the plains of Thrace, lying south of the Balkans, over toward the Black Sea and above Constantinople, the rest of the peninsula is almost entirely one confused tangle of craggy mountains, interspersed throughout with small, fertile valleys and plateaus.  This roughness of surface becomes especially aggravated as one passes westward, and over toward the Adriatic coast, from Greece up into the Austrian province of Dalmatia, the country is almost inaccessible to ordinary travelers.

What is the political value of this beleaguered domain?  The broad, significant fact is that any road from western Europe to the Orient must pass through the Balkan Peninsula, and that these mountains almost block that road.  From north to south there is just one highway, so narrow that it is really a defile.

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.