In 1735 Francisco de San Buenaventura y Tejada, appointed auxiliary to the Bishop of Santiago de Cuba in 1731, finally arrived in Florida. When he was translated to the See of Yucatan in 1745, Pedro Ponce y Carrasco was named his successor but did not sail to Florida until nine years later. Once there, he remained only nine months. In 1762-1763, on the eve of its cession to England, the territory received an impromptu episcopal visitation by Bishop Pedro Augustin Morrell of Santiago de Cuba as he was returning from English captivity by Charleston, South Carolina.

While acquiring Florida from Spain, England in 1763 also acquired from France a thin strip of territory extending westward along the Gulf to the Mississippi. By a royal proclamation of the same year two royal colonies were formed of the territory thus acquired: East Florida, which extended west to the Charrahoochee River and had St. Augustine as its capital, and West Florida, which extended west from the Chattahoochee River to the Mississippi and had Pensacola as its capital. Although the British sovereign pledged to allow Catholics freedom of worship insofar as the laws of Great Britain permitted, a wholesale exodus of the Spanish population took place, and as a result Catholicism all but disappeared from the area. A small revival came five years later when Andrew Turnbull, a Scottish physician turned colonizer, established a plantation composed largely of Catholic Minorcans at New Smyrna on the Atlantic coast, seventy-four miles south of St. Augustine.

Before long the territory was once again in Spanish hands. In 1779 Spain officially threw in her lot with the American revolutionaries and attacked British West Florida. Mobile fell to her in 1780 and Pensacola in 1781. The remainder of the Floridas was returned to her by treaty in 1783. Once again under the ecclesiastical jurisdiction of the Bishop of Santiago de Cuba, the Church in the territory was confronted with a twofold task: the reduction of Spaniards, Minorcans and French to ecclesiastical unity under the Spanish Patronato Real and the conversion of Anglo-American settlers. While Bishop Santiago Joseph de Hechavarria y Elguezua of Santiago de Cuba was primarily responsible for ecclesiastical affairs in these remote areas of his diocese, the actual supervision was entrusted to two vicarios, Father Thomas Hassett, an Irish priest from Spain, who was sent to reside at St. Augustine and care for East Florida, and Father Cirilo Sieni de Barcelona who resided in New Orleans and was charged with the care of the joint province of Louisiana - West Florida.

By this time, the Spanish authorities had come to recognize the need for a resident bishop on the mainland. A proposal was drawn up for the appointment of an auxiliary to the Bishop of Santiago de Cuba to reside in New Orleans. The plan was approved by Rome and in 1781 King Charles III of Spain asked Bishop Hechavarria to propose Father Cirilo for the post. Although Cirilo was officially notified of this appointment on July 18, 1782, bulls were not issued by Pope Pius VI until June 6, 1784, and Cirilo's consecration did not take place until March 6, 1785.

Meanwhile, it had become evident that the administrative work of the vast Diocese of Santiago de Cuba was too great a burden for its bishop. Eventually, by a consistorial decree of September 10,1787, that diocese was split in two and the new Diocese of St. Christopher, with its episcopal seat at Havana, was erected. The mainland territories of Louisiana and the Floridas were placed under its jurisdiction. Bishop Felipe Joseph Trespalacios of Puerto Rico was transferred to the new diocese and Bishop Cirilo became his auxiliary. Subsequent events, marred by friction between the two bishops, soon demonstrated the unfeasibleness of such a division of authority. By 1791 King Charles IV had decided upon a further division of the Diocese of St. Christopher. Rome was consulted and on April 25, 1793, Pope Pius VI issued a bull establishing the Diocese of Louisiana and the Floridas. Auxiliary Bishop Cirilo was recalled and Luis Ignacio Maria de Penalver y Cardenas, a forty-four-year-old native of Havana, was named bishop.

Consecrated at Havana on April 25, 1795, Bishop Penalver arrived in New Orleans on July 17 and took formal possession of his See on July 24. He was confronted immediately with a multitude of distressing problems. A general spirit of indifference and even scorn for religion, fostered in part by the spread of Voltairianism and revolutionary ideologies from France, combined with the perennial shortage of priests, the distinct aversion of the French population for everything Spanish, and the deeply rooted moral abuses that had developed under pioneer colonial conditions to burden the bishop during his six-year administration of the diocese. Eventually, even his great zeal could no longer sustain him in the face of such appalling conditions and he petitioned the king for a change to some other diocese. His request was granted. On July 29, 1801, Rome formally announced his appointment to the Archdiocese of Guatemala. Envisioning only a brief interval before the arrival of a successor, he appointed Father Thomas Hassett administrator and Father Patrick Walsh assistant administrator before leaving Louisiana in November of that same year.

Events were to prove Penalver's prognostication wrong and to undermine the arrangements he had made for the interim administration of the vacant See. Louisiana was to be without a bishop for the next fourteen years. Although Francisco Porro y Peinado, a Spanish Minim, was selected for the post early in 1801, rumors of the impending transfer of Louisiana from Spain to France caused him to delay his departure. Eventually in 1803, before he had ever formally taken possession of the diocese, he was transferred to the Diocese of Tarazona in Spain. The unexpected duration of the period of administration and the complications created by the retrocession of the Louisiana Territory to France and its subesequent sale to the United States in 1803, which brought to an abrupt end the close relationship that had existed between Church and State, combined to create for Father Hassett unexpected difficulties, not the least of which was an end to the financial subsidies which the state had granted to the Church under both the Spanish and French regimes.

The situation worsened upon the death of Hassett in 1804. Although Father Walsh then claimed authority by virtue of his appointment as assistant administrator, his claim was disputed by Father Anthonio de Sedella, the Capuchin rector of the Cathedral, who unfortunately had a substantial popular following. Likewise, in 1806 Bishop Juan Jose Dias de Espada of Havana disputed Walsh's authority in Florida which had remained Spanish territory. Although Rome in 1806 had authorized Bishop John Carroll of Baltimore to assume temporary supervision of the vacant See, the extent of his jursidiction was not specifically spelled out, and as a result it was not clear whether Florida was included in the territory entrusted to him. The Bishop of Havana continued to exercise jurisdiction over Florida, and in Louisiana the authority of the administrators appointed by Carroll continued to be challenged by Father Sedella and his followers. Finally, in 1815 Louis-Guillaume-Valentin DuBourg, who had been acting as administrator, was named bishop. Although even his authority was contested at times by Sedella and although the question of Florida remained unsettled until the transfer of the territory to the United States in 1821, the diocese once again had a bishop.

Brief general accounts of the Catholic Church in colonial Louisiana and Florida may be