John Philip Sousa (/ˈsuːsə/; Portuguese pronunciation: [ˈsouzɐ] (November 6, 1854 – March 6, 1932) was an American composer and conductor of the late Romantic era, known primarily for American military and patriotic marches. Because of his mastery of march composition, he is known as "The March King" or the "American March King" due to his British counterpart Kenneth J. Alford also being known as "The March King". Among his best-known marches are "The Liberty Bell", "The Thunderer", "The Washington Post", "Semper Fidelis" (Official March of the United States Marine Corps), and "The Stars and Stripes Forever" (National March of the United States of America).

Sousa's father was Portuguese, his father was born in Açores, Portugal and his mother of Bavarian ancestry. Sousa began his career playing violin and studying music theory and composition under John Esputa and George Felix Benkert. His father enlisted him in the United States Marine Band as an apprentice in 1868. After departing the band in 1875, Sousa learned to conduct. From 1880 until his death, he focused exclusively on conducting and the writing of marches. He eventually rejoined the Marine Band and served there for 12 years as director. On leaving the Marine Band, Sousa organized his own band. He toured Europe and Australia and developed the sousaphone, a large brass instrument similar to the tuba. On the outbreak of World War I, Sousa was commissioned as a Lieutenant Commander and led the Naval Reserve Band in Illinois. Following his tenure, he returned to conduct the Sousa Band until his death in 1932.