Premise: "You're a Grand Old Flag" is an American patriotic march. The song, a spirited march written by George M. Cohan, is a tribute to the American flag. In addition to obvious references to the flag, it incorporates snippets of other popular songs, including one of his own. Cohan wrote it in 1906 for "George Washington, Jr.", his stage musical.
Hypothesis: "George Washington Jr." debuted in 1906.