John of Matha was a Provençal nobleman, educated at the University of Paris, and a young theologian when he was ordained priest. According to tradition, at his first Mass he received a vision of Christ holding the hands of two captives in chains — one Christian and one Moorish — and understood himself called to a new work: the ransom of Christian captives from the slave-markets of North Africa and Andalusia.
With the hermit Felix of Valois he founded in 1198 the Order of the Most Holy Trinity for the Redemption of Captives — confirmed by Pope Innocent III in the bull Operante divinae the same year. The Trinitarians wore a white habit with a red and blue cross (the colours symbolic of the Trinity) and bound themselves by a fourth vow: to give up to ransom their own freedom and even their lives.
Through the 13th century the Trinitarians and the slightly later Mercedarians together ransomed tens of thousands of captives from Tunis, Algiers, Salé, and the corsair ports of the western Mediterranean. John of Matha himself led several ransom expeditions across North Africa. He died at Rome in 1213 and was buried at the church of San Tommaso in Formis on the Caelian.