World War I was an international conflict primarily involving European nations that was fought between 1914 and 1918. The United States did not enter the conflict until April 1917, but its entry was the decisive event of the war, enabling the Allies (Great Britain, France, Italy, and Russia) to defeat the Central Powers (Germany, Austria-Hungary, Turkey, and Bulgaria). The leadership of President WOODROW WILSON led to both the conclusion of hostilities and the creation of the LEAGUE OF NATIONS, an international organization dedicated to resolving disputes without war.
The war began on July 28, 1914, when Austria-Hungary declared war on Serbia. During the late nineteenth century, European nations had negotiated military alliances with each other that called for mutual protection. The Austria-Hungary declaration of war triggered these alliance commitments, leading to the widening of the war between the Allies and Central Powers.
During the next four years, the war was fought primarily on three fronts and on the Atlantic Ocean. The western front was in France, where Germany was opposed by France, Great Britain, and eventually the United States. The eastern front was in Russia, where Germany and Austria-Hungary opposed Russia. The southern front was in Serbia and involved Austria-Hungary and Serbia.
In August 1914 Germany invaded Belgium and then moved into France. German forces were unable to achieve a decisive victory, however,
ever, and the war soon became a conflict of fixed battle lines. French, British, and German soldiers lived and fought in trenches, periodically making assaults on the enemy by entering the "no man's land" between the two sets of trenches. The use of machine guns, tanks, gas warfare, and artillery in these confined battlefields generated unprecedented human carnage on the western front.
Though Germany had more success on the eastern front, neither side had sufficient economic and military strength to achieve victory. In 1916 and early 1917, Wilson sought to bring about negotiations between the Allies and Central Powers that would lead, in his words, to "peace without victory." Wilson's efforts at first appeared promising, but German military successes convinced the Central Powers that they could win the war.
Germany's use of submarine warfare proved to be the key element in provoking the United States' entry into the war. In 1915 a German submarine had...