During his musical career, John Philip Sousa referred to the march “Semper Fidelis”, which he had composed in 1888 (probably during summer) as the official march of the United States Marine Corps. He also labeled the piece his “best march”. It has been the first statement that was questioned at times, as pertinent documentation is not available. John Philip Sousa was known to be an honorable man and he definitely had no reason to ruin his impeccable reputation. It is probable that written documents that assigned “Semper Fidelis” to the Marines as official march were lost during a flood at the beginning of the 20th century. In this context it is interesting to note that records are lacking showing Sousa’s military rank when he directed the Marine Band. In addition there neither are official data regarding his pay, nor when and where concerts were stated, and what musical programs were performed. Be it as it be, it goes without saying that “Semper Fidelis” is regarded the official march of the Marine Corps, as its title is taken from the motto of the Corps. The special position of the march is underlined by another event of importance: “Semper Fidelis” was played as a funeral march, when the Marine Band accompanied John Philip Sousa’s body on his way from the Marine Barracks to the Congressional Cemetery in 1932. Furthermore an interview by Sousa leaves room for questions. It was printed in the “Independent” on October 31, 1927 and reads: “I wrote ‘Semper Fidelis’ one night while in tears, after my comrades of the Marine Corps had sung their famous hymn in Quantico.” Sousa probably referred to a military exercise that took place in Quantico, and he did not speak of Quantico as a military post. Quantico became a post only in 1917. This means that more than quarter of a century elapsed between the composition of the march at the one hand, and the first assignment of Marines to this place. The drum roll and the trio of “Semper Fidelis“ go back to an exercise called “With Steady Step”. It was written as a drill piece and is contained in Sousa’s training manual “The Trumpet and Drum” for field trumpet and drum in 1886.