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.
Western Front in 1915
On the Western front neither France nor Great Britain was ready in 1915 to undertake any advance comparable with the great offensives of the Central Powers in the East. Russia in her agony complained that France was not doing enough, but all the Allies' efforts this year were crippled by their inability to supply the wholly unprecedented demands for munitions of war. Great Britain was still struggling months behind to catch up a foe who had been preparing for years. Mr. Lloyd George subsequently related how, in the month of May, 1915, when the Germans were turning out 250,000 shells a day, most of them high-explosives, Great Britain was producing a mere 2500 a day in high-explosives, and 13,000 in shrapnel. The French, accustomed to supplying the demands of armies on a Continental scale, had naturally done considerably better than this, but even their most strenuous efforts were inadequate to cope with the enormous output of the German arsenals. Mr. Lloyd George retired from the Chancellorship of the Exchequer in order to assume control of the newly created Ministry of Munitions, which in due course more than made good all these defects. That, however, was not in 1915. Up to the end of that year, according to Lord French, "the scanty supply of munitions of war paralysed all our power of initiative, and at critical times menaced our defence with irretrievable disaster".
At the end of the first long winter of dreary trench warfare the British Commander-in-Chief deemed it necessary to undertake an offensive in order to prevent the moral of his army from deteriorating. Hence the battle of Neuve Chapelle, which, begun on 10th March, was fought with a small reserve of ammunition accumulated for the purpose, and had to be broken off after three days' struggle through lack of further supplies. The troops chosen for the main assault were Rawlinson's Fourth Army Corps, with the Indian Corps on the right. Following the preliminary bombardment, they quickly overran Neuve Chapelle itself and made 1000 yards progress on a 3-mile front. But to left and right the attacks were held up, and two further days' fighting failed to add to the gains—purchased at the excessive cost of 562 officers and 12,239 men. The total German losses, including 1680 officers and men as prisoners, were estimated as rather higher than this, but the net result, though ranking as a British victory, was admittedly disappointing.
Earlier in the year Lord French had endeavoured to convince Joffre that the proper rôle for the British army to fulfil was an advance on the extreme north in co-operation with the British navy. Joffre was unsympathetic, though he held out hopes of co-operating in such an advance with the French army at a later date. His plan for the 1915 campaign was to break through the German line from the south at Rheims, and from the west at Arras. To do this he must mass as many French corps as possible behind these points, meanwhile keeping the enemy busy elsewhere in order to prevent
him from reinforcing the threatened positions. This general strategic idea, as Lord French has pointed out, was the foundation of all the Allied efforts in the West throughout 1915. It led to numerous local successes along many parts of the line, but no real advance was made towards the main objectives. These were not defined until the combined offensive was launched in September.
The Germans themselves, though content to leave to the Allies most of the attacking in the West in 1915, maintained a sufficiently active offensive-defensive. While the French in Alsace were making a fresh advance on Mulhouse at the beginning of the year, they counter-attacked at Soissons, after bombarding the cathedral on 9th Jan. It was only after a week's desperate fighting and heavy French losses—including a bridge-head on the Aisne—that they were checked. In Champagne the French managed to capture Perthes (8th Jan.), and strove valiantly but vainly to wipe out the St. Mihiel salient. The most ambitious effort of the opening months of the year was the British offensive at Neuve Chapelle, which, as already pointed out, failed largely through lack of ammunition. In his report on that battle the British Commander-in-Chief referred to the pressing need of "an almost unlimited supply of ammunition"; and the lack of it was the real explanation of the Allied failure in 1915.
Germany knew well enough how matters stood in this respect, and added ruthlessly to the handicap which their own superior supplies gave them by suddenly attacking with chlorine gas—the first use of poison-gas in the war. This was on 22nd April, following a grim struggle south-east of Ypres for Hill 60, the flattened remains of which, after five days' incessant fighting, remained in British possession. Having been careful beforehand to accuse the French of using poison-gas near Verdun on the 14th—a charge without justification—the Germans launched it in dense volumes from pipes previously laid down for the purpose north-east of Ypres. The attack was preceded by a heavy bombardment, the gas-clouds following at 5 p.m. on the 22nd. The Allied line was held at this point by French Colonial and Territorial troops, with the Canadian Division on their right. All unprotected as they were against this diabolical form of warfare, the French troops, gasping for breath, broke and fled. Many fell asphyxiated. With a gap in the Allied line 5 miles wide, the Canadians suddenly found their flank left in the air. Less affected by the gas than the French, they were chiefly instrumental in saving the situation by a valiant resistance until reinforcements could be sent to fill the gap.