With the fall of Serbia came the collapse of Montenegro, in circumstances considerably less heroic than those which marked the Serbian retreat. The key position of Mont Lovtchen was abandoned to the Austrians with little if any show of resistance, and Cettinje, the capital, similarly entered by the invaders. King Nicholas of Montenegro sought refuge in Paris; Prince Mirko of Montenegro in Vienna.
The Serbian soldiers who survived the great retreat, numbering some 100,000 in all, were met on the Adriatic coast by units of the Italian fleet and transferred to Corfu--to recoup and refit for the later campaigns which were to lead to the recovery of their country.
Italy, whose warships were thus instrumental in salving the Serbian army, had thrown in her lot with the Allies by declaring war against Austria-Hungary on 23rd May, 1915. Austria had refused to offer adequate 'compensation' for her disturbance of the Balkans; and, moreover, the time had obviously arrived to complete Italian unity. A few weeks previously Italy had signed the Treaty of London, under which the Allies agreed to satisfy most of her territorial ambitions when the time came to share the spoils of victory an agreement which led to some of the most difficult problems in the final peace settlement. To Italy's honour be it added that she joined forces with the Allies when their prospects were none too bright, when they were able to report little or no progress either on the Western front or in Gallipoli, and Austro-German arms, on the other hand, were beginning to carry all before them in Mackensen's great drive in Galicia.
Italy was in no position to throw her whole weight into the struggle in 1915. Though her war strength was reckoned at a million men, her army was ill-equipped with guns, especially with modern heavy artillery and machine-guns, and her industrial resources were wholly inadequate to make good the deficiency. The mountainous frontier which she had to defend, too, gave every advantage to the Austrians. She succeeded in seizing three of the passes, the Stelvio, Tonale, and Guidriari, on the east side of the Trentino, and in blocking others on the west side, as the opening moves of her campaign, the object being to secure her flank in the subsequent offensive operations which aimed at Trieste by an advance across the Isonzo. Though these operations succeeded in pinning to the Italian front considerable forces of Austro-Hungarian troops which might have been thrown into the Russian furnace, the Italian effort fell far short of its objectives. General Cadorna, the Italian Commander-in-Chief, won a number of small successes in deploying his Third Army on the right bank of the Isonzo during June and July, securing the bridge-heads at Caporetto--the scene of Italian disaster two years later--Plava, Gradisca, and Monfalcone, thus holding the western bank of the river from Tolmino down to the sea. But the Italians were now faced with powerful defences, buttressed by the Carso Plateau in the south, which could only be carried at that time at prohibitive cost. All attempts to capture these strongholds broke down, and though a footing was gained on the Carso, and slight gains were constantly reported from the Trentino, the operations along the Italian front settled down before the year was out to the give-and-take fighting which characterized the siege operations in the West.