Uncle Sam is the common national personification of the American government or the United States in general. The first use of Uncle Sam in formal literature, as distinct from newspapers, was in the 1816 allegorical book "The Adventures of Uncle Sam in Search After His Lost Honor" by Frederick Augustus Fidfaddy. An Uncle Sam is mentioned as early as 1775, in the original "Yankee Doodle" lyrics of the American Revolutionary War. It is not clear whether this reference is to Uncle Sam as a metaphor for the United States, or to an actual person named Sam. The lyrics as a whole celebrate the military efforts of the young nation, besieging the British at Boston.
The Uncle Sam we know so well today didn't get a standard appearance until the well-known "recruitment" image of Uncle Sam was created by James Montgomery Flagg (inspired by a WWI British recruitment poster showing Lord Kitchener in a similar pose). It was this image more than any other that set the appearance of Uncle Sam as the elderly man with white hair and a goatee wearing a white top hat with white stars on a blue band, a blue tail coat and red and white striped trousers.
The image of Uncle Sam was shown publicly for the first time, according to some, in a picture by Flagg on the cover of the magazine Leslie's Weekly, on July 6, 1916, with the caption "What Are You Doing for Preparedness? More than four million copies of this image were printed between 1917 and 1918. Flagg's image also was used extensively during World War II during which the U.S. was codenamed 'Samland' by the German intelligence agency Abwehr.
DYK- J. M. Flagg's 1917 poster, based on the original British Lord Kitchener poster of three years earlier, was used to recruit soldiers for both World War I and World War II. Flagg used a modified version of his own face for Uncle Sam, and veteran Walter Botts provided the pose.
* Matthew Brady is from the Old Northwest Trading Company Images of War: Forever a Rebel set.