America in World War I

World war I involved many large nations in all different parts of the world. The name is commonly given to the wars of 1914–18 and 1939–45, although only the second of these was truly global.
By the spring of 1917, World War I had become a deadly war of attrition. Russia left the war that year, and after the Bolsheviks assumed power in the Russian Revolution of 1917, Russia signed a separate peace treaty with Germany in March 1918. Allied prospects looked grim. With Russia out of the picture, Germany shifted its troops to the western front, a north-south line across France, where a gruesome stalemate had developed. Dug into trenches and shelled by artillery, great armies bogged down in a form of siege warfare.
In June 1917 the American Expeditionary Force, led by General John J. Pershing, began to arrive in France. By March 1918, when Germany began a massive offensive, much of the American force was in place. Reluctantly, the United States allowed American troops to be integrated into Allied units under British and French commanders. These reinforcements bolstered a much-weakened defense, and the Allies stopped the German assault. In September 1918 American troops participated in a counteroffensive in the area around Verdun. The Saint-Mihiel campaign succeeded, as did the Allied Meuse-Argonne offensive, where both the Allies and the Germans suffered heavy casualties. Facing what seemed to be a limitless influx of American troops, Germany was forced to consider ending the war. The Central Powers surrendered, signing an armistice on November 11, 1918. Only the challenge of a peace treaty remained.
American manpower tipped the scales in the Allies’ favor. At war for only 19 months, the United States suffered relatively light casualties. The United States lost about 112,000 people, many to disease, including a treacherous influenza epidemic in 1918 that claimed 20 million lives worldwide. European losses were far higher. According to some estimates, World War I killed close to 10 million military personnel.
Summary: a war between the allies (Russia, France, British Empire, Italy, United States, Japan, Rumania, Serbia, Belgium, Greece, Portugal, Montenegro) and the Central Powers (Germany, Austria-Hungary, Turkey, Bulgaria) from 1914 to 1918