Patrick Gilmore
Patrick Sarsfield Gilmore was an Irishborn American composer and bandmaster who lived and worked in the United States after 1848. Whilst serving in the Union Army during the Civil War, Gilmore wrote the lyrics to the song When Johnny Comes Marching Home. This was published under the name Louis Lambert.
Gilmore was born in Ballygar, County Galway. He started his music career at age fifteen, and spent time in Canada with an English band. Already a fine cornet player, he settled in Boston, Massachusetts in 1848, becoming leader of the Suffolk, Boston Brigade, and Salem bands in swift succession. He also worked in the Boston music store of John P. Ordway and founed Ordways Aeolians, a group of blackface minstrels. With the Salem Band, Gilmore performed at the 1857 inauguration of President James Buchanan.
Source: Wikipedia