What does Boxing Day have to do with boxing?
1903, named for U.S. bandleader and composer John Philip Sousa (1854-1932).
The first sousaphone was made by C.G. Conn in 1899 expressly for Sousa's band and its bell opened directly upward. The present bell-front type was first made in 1908. ["International Cyclopedia of Music," 1939]