The founding-intention for the order was the ransom of Christians held captive by Muslims, a consequence of crusading and of piracy along the Mediterranean coast of Europe.

The period of the Crusades, when so many Christians were in danger of falling into the hands of Muslims, witnessed the rise of religious orders vowed exclusively to this pious work.

[6][7] Pope Innocent III granted the order and its rule approval with his letter Operante divine dispositionis clementia, issued on 17 December 1198.

In addition to the Order's purpose of ransoming Christian captives, each local community of Trinitarians served the people of its area.

Brother John's founding intention expanded quickly beyond the three initial foundations (Cerfroid, Planels, Bourg-la-Reine) into a considerable network of houses committed to the ransom of Christian captives and the works of mercy conducted in their locales.

[8] Among the earliest recruits were some Englishmen, and the first to go on the special mission of the order were two English friars, who in 1200 went to Morocco and returned to France with 186 liberated Christian captives.

The Rule's requirement of "the tertia pars", or setting aside one-third of all income for the ransom of Christian captives, became a noted characteristic of the Order.

Reforming interests and energies manifested themselves among Trinitarians in France with the foundation at Pontoise, north of Paris, during the last quarter of the sixteenth century.

[9] In succeeding centuries, European events such as revolution, government suppression and civil war had very serious consequences for the Trinitarian Order and it declined significantly.

Its members dedicated themselves to fostering and promoting devotion to the Holy Trinity, evangelising non-Christians, assisting immigrants, educating the young, and to parish work.

Today the Trinitarian family is composed of priests, brothers, women (cloistered nuns and active sisters) as well as committed laity.

Statutes attributed to William the Scotsman, the third Minister General of the Order (1217–1222), give some idea of the primitive organization of the Trinitarian Fraternity.