Rev. Charles Tindley (1851-1933), the self-proclaimed "Prince of Preachers," published "I Will Overcome Someday" in 1901. Tindley consciously or unconsciously borrowed parts of his melody from the 18th-century Catholic hymn "O Sanctissima," translated into German as "O du frohliche." I have read that it remains a popular Catholic Marian hymn to this day:

   O sanctissima, O piissima,
   Dulcis Virgo Maria.
   Mater amata, intemerata,
   Ora, ora pro nobis

-Adam Miller
Folksinging.org