Frontiers.—Yugoslavia is of trapezoidal shape, the long axis having a N.W.-S.E. direction. The south-eastward extension is narrowed by Albania, which separates Old Serbia and Serbian Macedonia from the Adriatic. The national seaboard extends from the river Fiumara, on which stands the Italian port of Fiume, to the river Bojana, which forms the frontier with Albania. Owing to the numerous islands and peninsulas, the latter with long border ing channels, the coast has a total length of nearly i,000 miles.
Of the four sides of the trapezium the northern one abuts, from west to east, on Austria, Hungary and Rumania. Strategically it is the weakest of all the frontiers, but this means that there is easy communication with the adjacent states and with Central Europe in general. The Hungarian section (353 m.) of this fron tier is the longest, and is traversed by the most important lines of rail. The Austrian frontier (16o m.) is short but is again tra versed by important railway lines. The Rumanian section (337 m.) falls into two parts, the old Danube frontier with Serbia and the new one in the Banat.
To the east Yugoslavia marches with Bulgaria, and this frontier (283 m.) is strategically the strongest of all. Strategic changes have been made in the old Serbo-Bulgarian frontier in four places. In the north, in the Timok region, a slight rectification had for its object the affording of greater protection to the railway which fol lows the Timok valley from Knjaievac and ZajeCar to Negotin and thus to the Danube below the obstacle of the Iron Gate. Formerly this railway was close to the frontier. The other changes have been made in the region of Caribrod, where the Nig-Sofia railway line crosses the frontier ; to the east of Vranje ; and in the Strumica region.
To the south the frontier with Greece (152 m.) remains that agreed upon between Greece and Serbia in 1913. The Albanian part (277 m.) of the western frontier is similarly in essentials that laid down by the Conference of Ambassadors at London in 1913.
The north-western frontier with Italy (132 m.) has only been settled with a considerable degree of difficulty, particularly in the Fiume region, where only the small port of Baros with the delta region remains to Yugoslavia. The frontier is not drawn on a linguistic basis, large numbers of Croats and Slovenes being included within the borders of enlarged Italy.
Within these boundaries Yugoslavia has an extreme range in latitude of from N., and in longitude of from about 14°-23° E.
Communications.—A section of the main European highway passes through Belgrade, branching at Nig for Constantinople and Salonika respectively. Thus the new state had not to improvise a national system from the cut fragments of routes which converged on centres outside the national territories, for a main trunk line was already present.
In the northern area Yugoslavia obtained in the first place that part of the Belgrade-Budapest route which runs via Novi Sad to Subotica. This section was already linked to an important east
west trunk line, with many branches, which follows broadly the Sava valley. Thus Zagreb (130,000) the second city of the king dom, lying in the Sava valley, had direct connection with Belgrade (250,000), as had also Ljubljana further west. Zagreb was also connected, if by a somewhat difficult route, to the Hungarian port of Fiume, and directly to Budapest. Ljubljana (53,000) had similarly railway connections both to Fiume and to Trieste and directly to Vienna through Maribor.
Further, southern Hungary had an excellent system of water ways, and just as Belgrade was linked to the Hungarian railway net because of its position, so also that position makes it the centre of the waterways. Navigation is possible on the R. Sava to Sigak, south-east of Zagreb ; on the Danube ; on the Tisa ; and on the Drava as far as Barcs on the left or Hungarian bank of the river. In addition the Voyvodina contains a number of canals, constructed to function both as means of irrigation and as water ways. Again, the navigable Sava receives a number of powerful tributaries from forested Bosnia, well fitted for floating timber.
Conditions are different in Bosnia where Austrian policy in railway construction was determined by political motives. It was not to Austria's interest to facilitate communication between Turkish lands and Bosnia, and there is not even now any railway through what used to be the sanjak of Novipazar. From Skoplje in Serbian Macedonia a railway runs towards Novipazar, but this line ends "in the air" at Mitrovica. Again, since the Bosnians, whether Muslims or not, are Slays, it was contrary to Austria's interest to permit of any direct connection being made between Serbia and Bosnia. A possible route does, however, occur between the Morava valley and Sarajevo (66,000). The Morava has a large left-bank tributary, the Western or Serbian Morava, which flows in a generally west-to-east direction, and opens up a line of communi cation into western Serbia. A Serbian railway was built from the Belgrade-Nig route along this valley line, which ended blindly at tiiice, near the Serbian-Bosnian frontier. Within Bosnia feeders of the River Drina made it easy to construct a line from Sarajevo of similar direction. This line, however, stopped at Vigegrad, a short distance from the frontier. By filling up the Uiice-Vigegrad gap Yugoslavia was able to connect Sarajevo to the main Belgrade Nig line. Further, there is a connection from ParaCin on that line to ZajeCar in the Timok valley, already mentioned. Since the Zajear line runs down to the Danube near Negotin there is thus a transverse connection from Sarajevo to the navigable section of the Danube below the Iron Gate and thus to the Black sea.