The reform of the Trinitarian Order was the work of St. John Baptist of the Conception (1561-1613). In Valdepeñas (Ciudad Real - Spain) he established the first community of the discalced Trinitarians. With the Brief Ad Militantes Ecclesiae, Pope Clement VIII gave ecclesial validity to the Congregation of the reformed and discalced brothers of the Order of the Most Holy Trinity, instituted to observe with all its vigor the Rule of St. John of Matha.

John Baptist of the Conception founded 18 convents of religious and one of cloistered Sisters. He lived and transmitted to his sons an intense spirit of charity, prayer, recollection, humility and penance, placing special interest in keeping alive the solidarity delivery to the captives and to the poor. The relation of the Trinitarians with the Trinity, as a vital center and source of redemptive charity, is a central theme in his life and teachings.