Armistice declared on the eleventh hour of the eleventh day of the eleventh month of the Year of Our Lord, 1918 to effect the cessation of hostilities in the "war to end all wars". (How's that been working out?)
Anyway, the war, now known as WWI, officially ended the following June upon the signing of the Treaty of Versailles.
In 1919, November 11 was declared by President Wilson to be "Armistice Day". It was made a legal holiday by an Act of Congress in 1938. In 1954, the day was declared by an Act of Congress and a Proclamation by President Eisenhower to be "Veterans Day" in honor of all who served in the Armed Forces, since the 'war to end all wars' had failed miserably to accomplish the goal of ending all wars.
The Uniform Holiday Act of 1968 attempted to catch Veterans Day into the "Monday" federal holiday program, and Veterans Day was celebrated on October 25, 1971. It quickly became apparent that the American people would not stand still for this confusing slight to a much respected and honored holiday. Thus, in 1975, President Ford signed an Act of Congress into law which returned the celebration of our Service People to November 11, and since 1978 it has been so observed.
To all who served our country in the Armed Forces, thank you, thank you. Were it not for your sacrifices, we would be enslaved and impoverished. You stood up for us when we needed you.