Italy and the Italian front, 1915–16
Great Britain, France, and Russia concluded on April 26, 1915, the secret Treaty of London with Italy, inducing the latter to discard the obligations of the Triple Alliance and to enter the war on the side of the Allies by the promise of territorial aggrandizement at Austria-Hungary’s expense. Italy was offered not only the Italian-populated Trentino and Trieste but also South Tirol (to consolidate the Alpine frontier), Gorizia, Istria, and northern Dalmatia. On May 23, 1915, Italy accordingly declared war on Austria-Hungary.
The Italian commander, General Luigi Cadorna, decided to concentrate his effort on an offensive eastward from the province of Venetia across the comparatively low ground between the head of the Adriatic and the foothills of the Julian Alps; that is to say, across the lower valley of the Isonzo (Soc̆a) River. Against the risk of an Austrian descent on his rear from the Trentino (which bordered Venetia to the northwest) or on his left flank from the Carnic Alps (to the north), he thought that limited advances would be precaution enough.
The Italians’ initial advance eastward, begun late in May 1915, was soon halted, largely because of the flooding of the Isonzo, and trench warfare set in. Cadorna, however, was determined to make progress and so embarked on a series of persistent renewals of the offensive, known as the Battles of the Isonzo. The first four of these (June 23–July 7; July 18–August 3; October 18–November 4; and November 10–December 2) achieved nothing worth the cost of 280,000 men; and the fifth (March 1916) was equally fruitless. The Austrians had shown on this front a fierce resolution that was often lacking when they faced the Russians. In mid-May 1916 Cadorna’s program was interrupted by an Austrian offensive from the Trentino into the Asiago region of western Venetia. Though the danger of an Austrian breakthrough from the mountainous borderland into the Venetian plain in the rear of the Italians’ Isonzo front was averted, the Italian counteroffensive in mid-June recovered only one-third of the territory overrun by the Austrians north and southwest of Asiago. The Sixth Battle of the Isonzo (August 6–17), however, did win Gorizia for the Italians. On August 28 Italy declared war on Germany. The next three months saw three more Italian offensives on the Isonzo, none of them really profitable. In the course of 1916 the Italians had sustained 500,000 casualties, twice as many as the Austrians, and were still on the Isonzo.
Serbia and the Salonika expedition, 1915–17
Austria’s three attempted invasions of Serbia in 1914 had been brusquely repulsed by Serbian counterattacks. By the summer of 1915 the Central Powers were doubly concerned to close the account with Serbia, both for reasons of prestige and for the sake of establishing secure rail communications with Turkey across the Balkans. In August, Germany sent reinforcements to Austria’s southern front; and, on Sept. 6, 1915, the Central Powers concluded a treaty with Bulgaria, whom they drew to their side by the offer of territory to be taken from Serbia. The Austro-German forces attacked southward from the Danube on October 6; and the Bulgars, undeterred by a Russian ultimatum, struck at eastern Serbia on October 11 and at Serbian Macedonia on October 14.
The western Allies, surprised in September by the prospect of a Bulgarian attack on Serbia, hastily decided to send help through neutral Greece’s Macedonian port of Salonika, relying on the collusion of Greece’s pro-Entente prime minister, Eleuthérios Venizélos. Troops from Gallipoli, under the French general Maurice Sarrail, reached Salonika on October 5, but on that day Venizélos fell from power. The Allies advanced northward up the Vardar into Serbian Macedonia but found themselves prevented from junction with the Serbs by the westward thrust of the Bulgars. Driven back over the Greek frontier, the Allies were merely occupying the Salonika region by mid-December. The Serbian Army, meanwhile, to avoid double envelopment, had begun an arduous winter retreat westward over the Albanian mountains to refuge on the island of Corfu.
In the spring of 1916 the Allies at Salonika were reinforced by the revived Serbs from Corfu as well as by French, British, and some Russian troops, and the bridgehead was expanded westward to Vodena (Edessa) and eastward to Kilkis; but the Bulgars, who in May obtained Fort Rupel (Klidhi, on the Struma) from the Greeks, in mid-August not only overran Greek Macedonia east of the Struma but also, from Monastir (Bitola), invaded the Florina region of Greek Macedonia, to the west of the Allies’ Vodena wing. The Allied counteroffensive took Monastir from the Bulgars in November 1916, but more ambitious operations, from March to May 1917, proved abortive. The Salonika front was tying down some 500,000 Allied troops without troubling the Central Powers in any significant way.
Major developments in 1916
The Western Front, 1916
In 1914 the centre of gravity of World War I had been on the Western Front, in 1915 it shifted to the Eastern, and in 1916 it once more moved back to France. Though the western Allies had dissipated some of their strength in the Dardanelles, Salonika, and Mesopotamia, the rising tide of Britain’s new armies and of its increased munition supplies promised the means for an offensive far larger in scale than any before to break the trench deadlock. Britain’s armies in France had grown to 36 divisions by the end of 1915. By that time voluntary enlistments, though massive, had nevertheless proved to be inadequate to meet Britain’s needs, so in January 1916, by the Military Service Act, voluntary service was replaced by conscription.
In December 1915 a conference of the leaders of the French, British, Belgian, and Italian armies, with representatives present from the Russian and Japanese armies, was held at Joffre’s headquarters. They adopted the principle of a simultaneous general offensive in 1916 by France, Great Britain, Russia, and Italy. But military action by Germany was to dislocate this scheme, and only the British offensive came fully into operation.
By the winter of 1915–16, Falkenhayn regarded Russia as paralyzed and Italy as inconsiderable. He considered the time at last ripe for positive action against France, after whose collapse Great Britain would have no effective military ally on the European continent and would be brought to terms rather by submarine warfare than by land operations. For his offensive in the West, however, Falkenhayn clung always to his method of attrition. He believed that a mass breakthrough was unnecessary and that instead the Germans should aim to bleed France of its manpower by choosing a point of attack “for the retention of which the French Command would be compelled to throw in every man they have.” The town of Verdun and its surrounding complex of forts was chosen, because it was a menace to the main German lines of communications, because it was within a French salient and thus cramped the defenders, and because of the certainty that the French would sacrifice any number of men to defend Verdun for reasons of patriotism associated with the town itself.
The keynote of Falkenhayn’s tactical plan was to place a dense semicircle of German heavy and medium artillery to the north and east of Verdun and its outlying fortresses and then to stage a continuous series of limited infantry advances upon the forts. These advances would draw the French infantry into defending or trying to retake the forts, in the process of which they would be pulverized by German artillery fire. In addition, each German infantry advance would have its way smoothed by a brief but extremely intense artillery bombardment that would clear the targeted ground of defenders.
Although French Intelligence had given early warnings of the Germans’ offensive preparations, the French high command was so preoccupied with its own projected offensive scheme that the warning fell on deaf ears. At 7:15 am on Feb. 21, 1916, the heaviest German artillery bombardment yet seen in the war began on a front of eight miles around Verdun, and the French trenches and barbed wire fields there were flattened out or upheaved in a chaos of tumbled earth. At 4:45 pm the German infantry advanced—although for the first day only on a front of two and a half miles. From then until February 24 the French defenders’ lines east of the Meuse River crumbled away. Fort-Douaumont, one of the most important fortresses, was occupied by the Germans on February 25. By March 6, when the Germans began to attack on the west bank of the Meuse as well as on the east bank, the French had come to see that something more than a feint was intended. To relieve the pressure on France, the Russians made a sacrificial attack on the Eastern Front at Lake Naroch (see below The Eastern Front, 1916); the Italians began their fifth offensive on the Isonzo (see above Italy and the Italian front, 1915–16); and the British took over the Arras sector of the Western Front, thus becoming responsible for the whole line from the Yser southward to the Somme. Meanwhile, General Philippe Pétain was entrusted with commanding the defense of Verdun. He organized repeated counterattacks that slowed the German advance, and, more importantly, he worked to keep open the one road leading into Verdun that had not been closed by German shelling. This was the Bar-le-Duc road, which became known as La Voie Sacrée (the “Sacred Way”) because vital supplies and reinforcements continued to be sent to the Verdun front along it despite constant harassment from the German artillery.
Slowly but steadily the Germans moved forward on Verdun: they took Fort-Vaux, southeast of Fort-Douaumont, on June 7 and almost reached the Belleville heights, the last stronghold before Verdun itself, on June 23. Pétain was preparing to evacuate the east bank of the Meuse when the Allies’ offensive on the Somme River was at last launched. Thereafter, the Germans assigned no more divisions to the Verdun attack.
Preceded by a week’s bombardment, which gave ample warning of its advent, the Somme offensive was begun on July 1, 1916, by the 11 British divisions of Rawlinson’s new 4th Army on a 15-mile front between Serre, north of the Ancre, and Curlu, north of the Somme, while five French divisions attacked at the same time on an eight-mile front mainly south of the Somme, between Curlu and Péronne. With incredibly misplaced optimism, Haig had convinced himself that the British infantry would be able to walk forward irresistibly over ground cleared of defenders by the artillery. But the unconcealed preparations for the assault and the long preliminary bombardment had given away any chance of surprise, and the German defenders were well prepared for what was to come. In the event, the 60,000 attacking British infantrymen moving forward in symmetrical alignment at a snail’s pace enforced by each man’s 66 pounds (30 kilograms) of cumbrous equipment were mowed down in masses by the German machine guns, and the day’s casualties were the heaviest ever sustained by a British army. The French participants in the attack had twice as many guns as the British and did better against a weaker system of defenses, but almost nothing could be done to exploit this comparative success.
Resigning himself now to limited advances, Haig concentrated his next effort on the southern sector of his Somme front. The Germans’ second position there (Longueval, Bazentin, and Ovillers) fell on July 14, but again the opportunity of exploitation was missed. Thenceforward, at great cost in lives, a methodical advance was continued, gaining little ground but straining the German resistance. The first tanks to be used in the war, though in numbers far too small to be effective, were thrown into the battle by the British on September 15. In mid-November early rains halted operations. The four-month Battle of the Somme was a miserable failure except that it diverted German resources from the attack on Verdun. It cost the British 420,000 casualties, the French 195,000, and the Germans 650,000.
At Verdun, the summer slackening of German pressure enabled the French to organize counterattacks. Surprise attacks directed by General Robert-Georges Nivelle and launched by General Charles Mangin’s army corps recovered Fort-Douaumont on October 24, Fort-Vaux on November 2, and places north of Douaumont in mid-December. Pétain’s adroit defense of Verdun and these counterattacks had deprived Falkenhayn’s offensive of its strategic fulfillment; but France had been so much weakened in the first half of 1916 that it could scarcely satisfy the Allies’ expectations in the second. Verdun was one of the longest, bloodiest, and most ferocious battles of the war; French casualties amounted to about 400,000, German ones to about 350,000.