“Onward, Christian Soldiers” is a 19th-century English hymn written by Sabine Baring-Gould in 1865. The music was composed by Arthur Sullivan in 1871.
Sullivan named the tune “St. Gertrude,” after the wife of his friend Ernest Clay Ker Seymer, at whose country home he composed the tune. The Salvation Army adopted the hymn as its favoured processional. The piece became Sullivan’s most popular hymn. The hymn’s theme is taken from references in the New Testament to the Christian being a soldier for Christ, for example II Timothy 2:3 (KJV): “Thou therefore endure hardness, as a good soldier of Jesus Christ.”