The Western Front.—During the winter of 1916-1917 there was little infantry warfare in France, although the heavy guns kept up their cannonades. In the spring of 1917 the Allies planned a great drive on the enemy positions in the valley of the Somme. But in March the Germans began a general retirement to a more easily defended line—the so-called Hindenburg line—on a front of one hundred miles, from Arras (ar-rahss´) to Soissons (swah-sawn´)[3]. Completely destroying the villages, churches, castles, vineyards, and orchards, they left a desolate waste behind them. In this retreat the Germans gave up French territory to the extent of thirteen hundred square miles.

The German retirement was closely followed by British and French troops. Great courage was shown by Canadian troops in the taking of Vimy Ridge on April 9. In the following month many attacks were made by the British and French, which resulted in the taking of nearly 50,000 prisoners and large quantities of munitions, and the breaking through the Hindenburg line in one place. During the summer and fall the Allied attacks continued to win small territorial gains. The artillery fire was very heavy during all this time. During a period of three weeks the French city of Rheims (reemz or rănss) alone, with its magnificent cathedral almost in ruins, was bombarded with 65,000 large caliber German shells.

Two very important ridges, from which artillery could reach German positions, were taken during the heavy fighting in November. The French forced a retreat of the Germans over a thirteen-mile front and occupied the ridge known as Chemin des Dames (shmăn dā dahm); while the Canadians secured Passchendaele (pahss-ken-dĕl´ā) Ridge.

Late in the year the British introduced a new method of warfare. Instead of beginning their attack with a great bombardment lasting many hours and thus indicating to the enemy the approximate time and place of attack, they sent over the front a large number of "tanks" which broke through the barbed wire entanglements and opened the way for the infantry. By this means the British successfully surprised the enemy in the battle of Cambrai (cahn-brĕ´; November 20 to December 13). Unfortunately they could not hold most of the land occupied,—which was lost later in the battle,—but they did show the possibility of breaking the old deadlock of trench righting. The new method was to be used by both sides during the campaigns of the following year.

The War in the Air.—During this year warfare in the air continued to advance. Guynemer (geen-mĕr´), the great French ace, who was lost on September 11, had to his credit the destruction of fifty-four enemy machines. The increase in the number of airplanes led to the grouping of large numbers into regular formations (escadrilles), sometimes composed of over a hundred planes. Each year showed a steady increase in the effectiveness of this kind of warfare. In 1916 a total of 611 enemy machines had been destroyed or damaged by the Allied forces. In 1917 the French destroyed forty-three in twenty-four hours; and the British brought down thirty-one enemy planes in one combat. In a single week in 1918 the Allies destroyed 339 German planes. On one day, October 9, 1918, three hundred and fifty airplanes were sent forth by the American army in a single bombing expedition.

The Russian Revolution.—In 1917 the Allied cause received a heavy blow through the collapse of the Russian government. Long before the war there had been parties in Russia which desired to do away with the autocratic government of the Czar and substitute some sort of representative system which would give to the people a voice in the management of their affairs. These reforming parties did not agree among themselves as to the kind of government they wished to set up; their ideas extended from limited monarchy of the English type, all the way to anarchy, which means no government at all. In 1905 the Czar met the wishes of the reformers to the extent of establishing the Duma, a sort of representative assembly or parliament, which should help in making the laws. The Duma, however, was never given any real authority, and as time passed those who believed in Russian democracy became more and more dissatisfied.

During the war the Germans by means of bribery and plotting did all they could to weaken the authority of the Russian government. There existed, moreover, much corruption and disloyalty among high Russian officials. As the war dragged on a shortage of food added to the general discontent. By the early months of 1917, conditions were very bad indeed, and dissatisfied crowds gathered in the streets of Petrograd. Hunger and hardship had made them desperate, and they refused to disperse until the government should do something to relieve the situation. Regiments of soldiers were summoned to fire upon the crowd. They refused to do so and finally joined the mob. Thus began the Russian Revolution.

At a meeting of the revolutionists a group of soldiers and working men was selected to call upon the Duma and ask that body to form a temporary government. Another committee was sent to inform Nicholas II that he was deposed. Messages were sent to the armies to notify the generals that there was no longer a Russian Empire and that they were to take their orders thereafter from the representatives of the Russian people. Within a few days the revolution was complete. On March 15, the Czar signed a paper giving up the throne of Russia. Moderate reformers were placed in charge of the different departments of the government. The new government was recognized by the United States, Great Britain, France, and Italy. It looked as if the revolution had established a free government for Russia and that thenceforth, as a democratic nation, she would fight better than ever by the side of her allies. In all the Russian provinces, elections were called for choosing delegates to an assembly that should make a new constitution for Russia.

Russia under Kerensky.—Meanwhile the extreme socialists began at once to make trouble for the new government. These men for the most part owned no property and wanted all wealth equally divided among the entire population. They considered the new government as tyrannical as that of the Czar had been. They also favored an immediate peace. Chief among the moderate leaders during this period was Alexander Keren´sky. He saw the necessity of keeping the revolution within bounds. For a while he was strong enough to maintain a moderate government in spite of the opposition of the extreme socialists. The Germans, meanwhile, through spies and secret agents, had been spreading among the Russian soldiers the idea that Germany was really their friend and that it was to their interest to stop fighting and retreat. Kerensky personally visited the battle front in Galicia, and for a time by means of his rousing speeches to the soldiers kept up their fighting spirit. New advances were made, the Germans and Austrians being driven back many miles. Lemberg itself seemed about to fall once more into the hands of the Russians. But this success was only temporary. Owing to the shortage of ammunition and the rapid spread of peace sentiments among the troops, the Russian army became disorganized and retreated from Galicia.

The Bolsheviki.—Bolsheviki (bōl-shĕv´e-kee) is the name given to the extreme socialistic party in Russia. From the beginning they had opposed the control of affairs by the moderate revolutionists under Kerensky. At last, in the fall of 1917, helped by the depression caused by the German advance and by the strikes and food riots which once more broke out in the capital, they succeeded in winning over to their side the Petrograd garrison and the navy, and drove Kerensky from the city (November 7). Their revolt was led by two of the most extreme members of the party, Lenine and Trotzky, who had at their disposal large sums of money furnished by Germany.