Phoebe Knapp was born on March 9, 1839, in New York City. She became a talented composer known for her music for hymns and as an organist. Throughout her life, she composed music for over five hundred hymns. Phoebe was married to Joseph Fairchild Knapp, a notable figure who helped found the Metropolitan Life Insurance Company. He supported her musical talents by having a pipe organ installed in their apartment, allowing her to compose comfortably.

Phoebe and Joseph attended the John Street Methodist Episcopal Church, where they met many influential people, including the hymn writer Fanny Crosby. Fanny and Phoebe became good friends and collaborated on several remarkable hymns. One of Phoebe’s most famous compositions is the melody for “Blessed Assurance,” written in 1873. They also worked together on the Palm Sunday hymn “Open the Gates of the Temple.”