The Russian Revolution
In March 1917, demonstrations in St. Petersburg culminated in the abdication of Tsar Nicholas II and the appointment of a weak centrist provisional government, which shared power with the socialists of the Petrograd Soviet. This division of power led to confusion and chaos, both on the front and at home, and the army became progressively less able to effectively resist the Germans. Meanwhile, the war, and the government, became more and more unpopular, and the discontent was strategically used by the Bolshevik party, led by Vladimir Lenin, in order to gain power.
The triumph of the Bolsheviks in November was followed in December by an armistice and negotiations with the Germans. At first, the Bolsheviks refused to agree to the harsh German terms, but when the Germans resumed the war and marched with impunity across Ukraine, the new government acceded to the Treaty of Brest-Litovsk on March 3, 1918, which took Russia out of the war and ceded vast territories including Finland, the Baltic provinces, Poland and Ukraine to the Central Powers.
1917 finally saw the entry of the United States into the war.
Entry of the United States
Early in 1917, Germany resumed its policy of unrestricted submarine warfare. This, combined with public indignation over the Zimmerman Telegram, led to a final break of relations with the Central Powers. President Woodrow Wilson requested that the United States Congress declare war, which it did on April 6, 1917. (Only one member of Congress, Jeanette Rankin of Montana, voted against the war).
The United States Army and the National Guard had mobilized in 1916 to pursue the Mexican “bandit” Pancho Villa, which helped speed up the mobilization. The United States Navy was able to send a battleship group to Scapa Flow to join with the British Grand Fleet, and a number of destroyers to Queenstown, Ireland, to help guard convoys. However, it would be some time before the United States forces would be able to contribute significant manpower to the Western and Italian fronts.
The British and French insisted that the United States emphasize sending infantry to reinforce the line. Throughout the war, the American forces were short of their own artillery, aviation, and engineering units. However, General John J. Pershing, American Expeditionary Force commander, resisted breaking up American units and using them as reinforcements for British and French units, as suggested by the Allies.
German Offensive of 1918
The entry of the U.S. into the war the previous year had made the eventual arrival of U.S. troops certain, while Russia’s withdrawal and the Italian disaster at Caporetto allowed the transfer of German troops to the West. Four successive German offensives followed, that of May 27 yielding gains before Paris comparable to the first advance.
On March 21, 1918, Germany launched a major offensive, “Operation Michael”, against British and Commonwealth forces. The German army developed new tactics involving stormtroopers, infantry trained in Hutier tactics (after Oskar von Hutier) to infiltrate and take trenches.
The Allies reacted by appointing French Field Marshal Foch to coordinate all Allied activity in France, and then as generalissimo of all Allied forces everywhere.
The German offensive moved forward 60 km and pressed the British lines so much that the British Expeditionary Force (BEF) commander, Field Marshal Sir Douglas Haig, issued a General Order on April 11 stating “With our backs to the wall and believing in the justice of our cause each one of us must fight on to the end.” However, by then, the German offensive had stalled because of logistical problems. Counterattacks by Canadian and ANZAC forces pushed the Germans back.