From the military point of view the Russian failure was even more serious than the French, because it came a year later, and at the hour when the superior numbers and resources of the enemies of Germany were already beginning to tell.
THE THIRD GERMAN OFFENSIVE
The two preceding German campaigns had been based on purely military considerations. The first was a true Napoleonic conception designed to grasp a Napoleonic opportunity. The second was partly imposed upon Germany by Russian success and Austrian failure. There was no longer a question of destroying the opponents in order, it was a question of eliminating one and then finding a basis for peace with the others. The third German campaign, that in the Balkans, was political quite as much as it was military. It was designed to provide Germany with some profit for her great sacrifices and her great losses, but it was no longer a question of the conquest of any considerable foe.
By the operations of British sea power, Germany had now practically lost her colonial empire. It was certain that with peace she would not again be permitted to make use of British colonies or ports, as she had done before. Her overseas commerce with belligerents and their colonies was bound to be ruined, even if peace came soon, for the period of the war it was, of course, abolished.
The entrance of Turkey on the German side had opened for the Germans a new field for industrial exploitation, if there could once be opened a road from the Danube to Constantinople. This field would be beyond the reach of sea power. Once Germany had taken actual command at Constantinople, once the railroad from Hamburg to the Bosphorus was open, it was possible to threaten Britain in Egypt, and perhaps ultimately in India by the Bagdad and Mecca railways.
Such a threat, coupled with one more successful campaign, might exercise a decisive influence upon the minds of the people of the allied countries, and in opening a road to the Golden Horn, Germany might find the path to peace. Already there was apparent willingness in Berlin to evacuate Belgium and northern France, only from Russia did Germany now insist upon tribute in the form of conquered provinces. But until the road to Constantinople was open, until the Serbian nuisance was abolished, peace could not be considered.
Turkey, too, was calling for aid. Early in the year the Anglo-French fleets had tried to force the Dardanelles. Their failure had been followed by a land attack at Gallipoli, which had so far failed, but Turkish ammunition and artillery was inadequate for a sustained fight, and there was needed German aid. To lose the Dardanelles was to see Turkey conquered, Russia provided with munitions, and the whole German dream of expansion to Asia Minor destroyed.
It was necessary, too, to provide the German people with a new victory. They had been bitterly disappointed that the Russian campaign had not brought peace, or, at the least, the elimination of Russia. A new and relatively cheap success, the conquest of the Balkans, would fire their imagination and again stimulate their hopes for a victorious peace. In addition, Bulgaria now beckoned to the Germans. Her army was at the disposition of the two kaisers, but there was plain peril that if the coming were too long delayed, the Allies might succeed in persuading Ferdinand to cast his lot with the camp that now offered him Serbian Macedonia and Turkish Thrace, and were suggesting the further pourboire of Greek Kavala.
Accordingly Germany decided to go south, having gone west and east without finding peace or decisive victory. She had available for this operation troops no longer needed against Russia since the campaign on this front had died out, and she had to command it, the great Mackensen, whose fame now rivaled that of Hindenburg, whose victories had regained Galicia. "Constantinople and Peace" became the new German watchword, just as "Paris and Peace" and "Warsaw and Peace" had been in preceding months.
And at the outset of this third campaign it is perhaps appropriate to point out that Germany was now to achieve that complete military success that had been denied to her in France and Russia, she was to win a victory in the military sense which was beyond cavil, but she was this time to lose the political profit she had hoped, because she had mistaken the importance in the minds of her enemies of the Balkan field and fatally overestimated the war weariness of the peoples that opposed her. At the Golden Horn she was to find not peace, but the necessity for new campaigns.
THE SERBIAN PHASE
On the military side the Serbian campaign was the simplest of operations. For many months the Serbian forces had been posted south of the Danube and the Save and east of the Drin, looking over their frontiers into Hungary and Bosnia. Behind them from the Danube at Belgrade to the Ægean at Saloniki ran the Orient railroad, by which they were munitioned. At Nish halfway to the sea, the line drew near to the Bulgarian frontier and sent a branch off, which passed through Bulgaria and reached Constantinople.
The Saloniki railway was the life line of Serbia, it was also the natural route for a retreat, if the Austro-German attack became too heavy. But it was fatally exposed, should Bulgaria enter the war against Serbia. In the Treaty of Bucharest, Greece and Rumania had undertaken to join Serbia should she be attacked by Bulgaria, and the mission of Greece was to cover the Saloniki railroad as far north as it was necessary to join hands with the Serbians.
Now, while the Bulgarians were beginning to mobilize and the Austro-German hosts were gathering to the north, Serbia appealed to her former allies to keep their agreement. Both declined, and their refusal was fatal. The Allies had relied upon Greek promises, and had failed to collect any considerable force at Saloniki. They had trusted Bulgaria and refused to let Serbia attack her neighbor before Bulgarian mobilization was complete. Once Bulgaria had mobilized the doom of Serbia was settled.
What happened was this: The Germans forced the passage of the Danube north and east of Belgrade and came south along the broad Morava River Valley, driving the Serbs before them. Thanks to the heavy artillery of the invaders Serbian resistance was impotent. The Austrians, meantime, crossed the Drin and came east from Bosnia. Think of Serbia as a rectangle and you can visualize two sides of the figure as closing in on the center, which was the heart of Serbia.
At the appointed moment the Bulgarians struck west from a third side of the rectangle, speedily crossed the Belgrade-Nish-Saloniki railroad, and thus cut off the true line of Serbian retreat, that upon Saloniki.
Very early in the campaign the Bulgars seized Uskub, thus interposing a wedge between the small Anglo-French force at Saloniki and the Serbs about Nish to the north of Uskub. Meantime a desperate concentration was taking place at Saloniki, and an Anglo-French force, commanded by Sarrail, was being pushed up the Saloniki railroad toward Uskub to open a road to the Serbs to join their allies. The operation suggested that successfully conducted in Flanders in the opening months of the war, which enabled the Belgian army to escape from Antwerp and join their allies in Flanders.
But this operation failed. The French came north to the outskirts of Veles, twenty miles from Uskub, just too late to save the Serbians, who now fled west to Monastir and south to Montenegro and Albania. As a fighting force the Serbs were eliminated, the wrecks of their armies barely escaping to the Adriatic and Ægean coasts at Durazzo and Saloniki. Bulgarian troops forced the Katchanik gorges and took Prisrend, and German and Austrian forces entered the ill-omened Plain of Kossovo and overran the ancient Sanjak of Novibazar.
Before the storm that was now moving south, the French and British retreated upon Saloniki, and presently began to construct about this Greek city lines and defenses recalling those Wellington built at Torres Vedras before Lisbon to restrain the flood of Napoleonic invasion in the Iberian peninsula. The conquest of the Balkan peninsula, save for Greece, was now as complete as Napoleon's own success in Spain had been more than a century before.
In due course of time an Austrian