World War I, which lasted from July 28, 1914 to Nov. 11, 1918, at one time was known as the Great War or "the war to end all wars" because not many could have imagined an even bloodier global conflict — World War II — would occur just two decades later.
Around 10 million soldiers were killed during World War I; over half of them were Allied forces, including 117,000 Americans. Countless more service members were injured, and an equal number — around 10,000 — civilians died or were injured.
The number of U.S. casualties undoubtedly would have been much higher, except the U.S. entered the war rather late, having favored a policy of neutrality.
On April 2, 1917, President Woodrow Wilson, who ran on the reelection slogan: "He kept us out of war," went before a joint session of Congress to request a declaration of war, citing Germany’s violation of its pledge to suspend unrestricted submarine warfare in the North Atlantic and the Mediterranean, as well as its attempts to entice Mexico into an alliance against the United States.
Four days later, Congress declared war on Germany. Congress, however, didn't declare war on one of Germany's most formidable allies, Austria-Hungary, until Dec. 7, 1917.
Within a few months, thousands of Americans were drafted for the war effort and were showing up at hastily constructed training installations across the nation. However, most of the more than one million U.S. troops didn't arrive in Europe until about a year later because the nation wasn't fully prepared or equipped for that scale of warfare.
The British and French commanders wanted Americans to fill their depleted ranks. However, U.S. Army Gen. John J. Pershing, American Expeditionary Forces commander, refused to have Americans serving under foreign command.
The one exception was that Pershing did allow African-American combat regiments to be used in French divisions. For example, the "Harlem Hellfighters" fought as part of the French 16th Division, and earned a unit Croix de Guerre medal for their actions at Chateau-Thierry, Belleau Wood and Sechault.
In 1918, the Germans went on a massive spring offensive, coming within just 75 miles of Paris. However, the Allied line held and even though Germany launched another big offensive over the summer, they were not able to regain the initiative. By that time, some 10,000 U.S. troops were arriving every day, and Germany's allies were beginning to defect or capitulate and an invasion of Germany itself seemed inevitable very soon.
The German government, sensing a looming defeat, signed an armistice on Nov. 11, 1918, at 11 a.m., ending the war. Formal ending of the war, however, occurred with the Treaty of Versailles on June 28, 1919.
Some notable technology firsts of World War I included:
- Tanks were employed by both sides.
- Aircraft were deployed by both sides for use in reconnaissance, air-to-air combat and limited use in bombing.
- Chemical warfare was used by both sides, including chlorine, mustard gas and phosgene. In response, gas masks were developed.
- Germany employed submarines, called U-boats, which were effective at sinking convoys of supply and troop ships. In response, the Allies developed depth charges, attack submarines and sonar.
- Narrow gauge railroads supplied food, ammunition and troops to the trenches on both sides, but motor vehicles were becoming increasingly common, and, after the war, became the transport of choice.
- Several aircraft carriers, then called seaplane carriers, were used in battle by the British, Japanese and Russians.
- Telephones and radios, known as wireless telegraph, were used by both sides, although messenger dogs and homing pigeons were still used for relaying messages.