Born in Massachusetts, Henry Franklin Belknap Gilbert studied composition with Edward MacDowell at the New England Conservatory. He also studied violin and piano, though he began a career in business upon his graduation from the conservatory.
After working as a printer, Gilbert began to assist Arthur Farwell with his Wa-Wan Press, a publishing company that was devoted to the publication and promotion of American music. Gilbert was a strong advocate for American music, as well as the use of folk melodies and humor in music, and gave lectures on the topic.
Gilbert's own music is a great example in the use of American folk music as material for classical music. Many of his pieces featured African American melodies, including his Comedy Overture on Negro Themes, which received international attention. He also employed Celtic and American Indian melodies in his music as well.
Gilbert's later music (pieces written after 1915) continued in the American tradition, though going even a little deeper. Several of these pieces were inspired by Walt Whitman, such as Gilbert's Whitmanesque Symphonic Piece (1925) and his Nocture After Whitman (1926).
Source: Nicholas E. Tawa's article in the New Grove Dictionary of Music and Musicians