Patrick Gilmore (born Dec. 25, 1829, County Galway, Ire.—died Sept. 24, 1892, St. Louis, Mo., U.S.) was a leading American bandmaster and a virtuoso cornetist, noted for his flamboyant showmanship, innovations in instrumentation, and the excellence of his bands.

Gilmore immigrated to the United States at age 19, and, after leading several bands, he took over the Boston Brigade Band (later known as Gilmore’s Band) in 1859. During the Civil War the entire band enlisted in the Union Army. He reorganized the Massachusetts Militia bands in 1863. In 1869 (National Peace Jubilee) and 1872 (World Peace Jubilee) he organized extravaganza performances with more than 10,000 performers. The one in 1869 featured cannon fire, church bells, and 100 firemen beating anvils in Giuseppe Verdi’s “Anvil Chorus.” From 1872 until his death he led the New York 22nd Regiment Band (also called Gilmore’s Band), with whom he toured Europe (150 concerts) in 1878.

Gilmore’s innovations in instrumentation brought the band from the heavy reliance on brass typical of the early 19th century to the higher proportion of reeds, especially clarinets, characteristic of 20th-century concert bands. He was also one of the first American bandmasters to conduct band arrangements of W.A. Mozart, Franz Liszt, and Gioacchino Rossini, in addition to the popular songs, marches, and dance tunes that made up the typical band repertoire. Gilmore reputedly composed “When Johnny Comes Marching Home” (1863) under the pen name Louis Lambert.