World War I – known at the time as “The Great War” - officially ended when the Treaty of Versailles was signed on June 28, 1919, in the Palace of Versailles outside the town of Versailles, France. However, fighting ceased seven months earlier when an armistice, or temporary cessation of hostilities, between the Allied nations and Germany went into effect on the eleventh hour of the eleventh day of the eleventh month. For that reason, November 11, 1918, is generally regarded as the end of “the war to end all wars.”

Soldiers of the 353rd Infantry near a church at Stenay, Meuse in France.

Soldiers of the 353rd Infantry near a church at Stenay, Meuse in France, wait for the end of hostilities. This photo was taken at 10:58 a.m., on November 11, 1918, two minutes before the armistice ending World War I went into effect

In November 1919, President Wilson proclaimed November 11 as the first commemoration of Armistice Day with the following words: "To us in America, the reflections of Armistice Day will be filled with solemn pride in the heroism of those who died in the country’s service and with gratitude for the victory, both because of the thing from which it has freed us and because of the opportunity it has given America to show her sympathy with peace and justice in the councils of the nations…"

The original concept for the celebration was for a day observed with parades and public meetings and a brief suspension of business beginning at 11:00 a.m.

The United States Congress officially recognized the end of World War I when it passed a concurrent resolution on June 4, 1926, with these words:

Whereas the 11th of November 1918, marked the cessation of the most destructive, sanguinary, and far reaching war in human annals and the resumption by the people of the United States of peaceful relations with other nations, which we hope may never again be severed, and

Whereas it is fitting that the recurring anniversary of this date should be commemorated with thanksgiving and prayer and exercises designed to perpetuate peace through good will and mutual understanding between nations; and

Whereas the legislatures of twenty-seven of our States have already declared November 11 to be a legal holiday: Therefore be it Resolved by the Senate (the House of Representatives concurring), that the President of the United States is requested to issue a proclamation calling upon the officials to display the flag of the United States on all Government buildings on November 11 and inviting the people of the United States to observe the day in schools and churches, or other suitable places, with appropriate ceremonies of friendly relations with all other peoples.

More: http://www1.va.gov/opa/vetsday/vetdayhistory.asp