"The Invincible Eagle" is an American military march composed in 1901 by John Philip Sousa and dedicated to the 1901 Pan-American Exposition held in Buffalo, New York.

[1] Sousa began composing the march during an evening train trip between Buffalo and New York City, sketching his ideas in a pocket notebook.

"Suddenly and without previous warning Mr. Sousa began to describe circles in the air with a pencil, jerking back and forth in his seat meanwhile.

Meanwhile Mr. Sousa furrowed his brow and from his pursed lips came a stirring air—rather a martial blare, as if hidden trombones, tubas, and saxophones were striving to gain utterance.

[I] looked on from over the top of a magazine and listened with enthusiasm as Mr. Sousa’s famous march, “The Invincible Eagle,” took form.