The first great campaign on the southeastern battle grounds of the Great War began on July 27, 1914, when the Austrian troops undertook their first invasion of Serbia. They crossed the Serbian border at Mitrovitza, about fifty miles northwest of Belgrade, driving the Serbians before them. The first real hostilities of the war opened with the bombardment of Belgrade by the Austrians on July 29, 1914--six days before the beginning of the campaigns on the western battle fields. We are now familiar with the theatre of war as described in the preceding chapters, and will now follow the first Austrian armies into Serbia. A stubborn fight excites the admiration of all observers, regardless of the moral qualities of the combatants. So, wherever our sympathies may lie, considering the war as a whole, there can be no doubt that the defense which the Serbians made against the first efforts of the Austrians to invade their country will stand out in the early history of the war as one of the most brilliant episodes of that period of the general struggle. Like a mighty tidal wave from the ocean the Austrian hosts swept over the Serbian frontier in three furious successive onslaughts, only to be beaten back each time. Naturally, there were material and moral causes, aside from the mere valor of the Serbians, which combined to create this disaster for the Austrian forces, but enough of the human element enters into the military activities of these campaigns to make them easily the most picturesque of the early period of the war. Before entering into a description of the actual events in 1914, it is well to consider the forces engaged. From a material point of view the Serbians entered into these campaigns greatly handicapped. They had lately been through two wars. In the First Balkan War they had not, it is true, been severely tested; the weight of the fighting had been borne by the Bulgarians in Thrace. The real test, and the great losses, came only with the second war, when the Serbian army threw every fiber of its strength against the Bulgarians in the Battle of the Bregalnitza, one of the most stubborn struggles in military history. The result was a Serbian victory, but it was very far from being a decisive and conclusive victory. The Bulgarians were forced back some fifteen miles into their own territory, but had it not been for the intervention of Rumania there can be no doubt that the Serbs would have entered Sofia. Here it was that the Serbians lost 7,000 killed and 30,000 wounded of their best men, as against 5,000 killed and 18,000 wounded in the whole war with Turkey; a total loss that was bound to be felt a few months later when the struggle was to be against so powerful an adversary as Austria-Hungary. The two previous wars had, without exaggeration, deprived the Serbian fighting forces of one-tenth their number--a tenth that was of the very best of first-line troops. [Illustration: Pictorial Map of the Balkans.]