Francis Xavier Seelos was born Johann Evangelist Seelos on January 11, 1819, in Füssen, Bavaria (Germany), into a devout Catholic family. Feeling called to serve both God and the immigrant poor, he studied philosophy and theology before emigrating to the United States in 1843 to join the Congregation of the Most Holy Redeemer (Redemptorists). He was ordained a priest in 1844 and soon became known for his gentle manner, intellectual clarity, and deep compassion, particularly toward German-speaking immigrants who faced hardship and isolation in their new homeland.

Father Seelos served in a variety of pastoral roles across the United States, including parish priest, seminary professor, novice master, and mission preacher. He worked closely with Saint John Neumann in Baltimore and later ministered in cities such as Pittsburgh, Cincinnati, Detroit, and New Orleans. Wherever he served, Seelos was sought out as a confessor and spiritual guide, known for his patience, kindness, and ability to explain the faith simply and clearly. His preaching emphasized God’s mercy and encouraged trust rather than fear, drawing many people—Catholic and non-Catholic alike—back to the sacraments.

In 1867, while serving in New Orleans during a yellow fever epidemic, Father Seelos contracted the disease after ministering to the sick and dying. He died on October 4, 1867, at the age of 48.