While the holiday is commonly printed as Veteran’s Day or Veterans’ Day in calendars and advertisements (spellings that are grammatically acceptable), the United States Department of Veterans Affairs website states that the attributive (no apostrophe) rather than the possessive case is the official spelling “because it is not a day that ‘belongs’ to veterans, it is a day for honoring all veterans.”
At the 11th hour on the 11th day of the 11th month of 1918, the Great War ends. At 5 a.m. that morning, Germany, bereft of manpower and supplies and faced with imminent invasion, signed an armistice agreement with the Allies in a railroad car outside Compiégne, France.
Greg