Born in the colony of Saint-Domingue, DuBourg was sent to France at a young age to be educated and entered the Society of Saint Sulpice.

In 1794, DuBourg sailed to the United States and began teaching and ministering in Baltimore, becoming the president of Georgetown College in Washington in 1795.

He also selected the site of Baltimore's first cathedral and became the ecclesiastical superior to Elizabeth Ann Seton's newly founded Sisters of Charity.

There, he built the first cathedral west of the Mississippi River and established missions to the American Indians, dozens of churches, and numerous schools, including St. Mary's of the Barrens Seminary and Saint Louis University.

Louis-Guillaume-Valentin DuBourg was born in the city of Cap-Français (known today as Cap-Haïtien) in the French Caribbean colony of Saint-Domingue, likely on 10 January 1766.

At the same time, he continued his studies at the College of Sorbonne,[9] and was ordained a priest by Antoine-Éléonor-Léon Leclerc de Juigné, the Archbishop of Paris, on 20 March 1790.

[5] The Spanish government believed French clergy were engaged in heterodox practices,[6] and restricted their ability to teach and publicly minister.

[4] In October 1795, just several months after arriving in the United States, DuBourg was appointed by Carroll to succeed Robert Molyneux as the third president of Georgetown College.

"[14] Seeking to make the school more cosmopolitan,[5] DuBourg recruited many students from Baltimore, particularly French refugees from the West Indies.

[4] DuBourg solicited financial support from Catholic donors,[5] which allowed him to sponsor sixteen students throughout his tenure to study at Georgetown in preparation for the seminary.

He promoted the school's public image by advertising its favorable situation upon a hill and proximity to Washington, D.C., the seat of the federal government.

DuBourg became active in Washington's high society, including making the acquaintance of Thomas Law, a merchant who enrolled his son at Georgetown.

[14] Through Law, DuBuissson received an invitation to dine with the former President George Washington at his home, Mount Vernon, in July 1797.

[18][5] Around this time, DuBourg also invited a group of Poor Clares who fled the revolution in France, and they founded a school for girls in the Georgetown area in 1798.

[22] Motivated in part by anti-French sentiment, the Maryland Jesuits eventually took steps to oust DuBourg in 1798, leading to his resignation.

[25][3] Though DuBourg initially intended the school to be open for general education, Bishop Carroll required that admission be limited only to West Indian students, so as not to compete with Georgetown College.

Work began in 1806, and DuBourg expedited the project by retaining Benjamin Henry Latrobe, the Architect of the Capitol, whose skilled Italian artists completed the building ini 1808.

With John Tessier, he also established a congregation for the many poor Black Baltimoreans who met and celebrated Mass at St. Mary's Chapel.

[33] In 1806,[4] DuBourg was in New York City to sell lottery tickets as a fundraiser for St. Mary's University, where he met the future saint Elizabeth Ann Seton, who he urged to travel to Baltimore to establish a school for girls.

[37] Before long, tensions arose between Seton and DuBourg, who forbade her from communicating with her mentor, a Sulpician priest, Pierre Babade.

Seton appealed DuBourg's instruction to John Carroll,[37] who referred the matter to Nagot, the Suplician superior in the United States.

[41] Upon arriving in New Orleans, he found the local Catholic population aligned with their pastor, a Capuchin priest, Antonio de Sedella.

[42] Sedella rejected the jurisdiction of Carroll, an American bishop, to appoint DuBourg as administrator over the French clergy in Louisiana.

Following the American victory, on 23 January 1815, Major General Andrew Jackson entered the city and was escorted by DuBourg into the St. Louis Cathedral, where he was greeted with a Te Deum hymn.

[46] He would continue his recruiting in Europe for two years,[5] and while in Lyon, France, he met a widow and expressed his desire to create an organization to raise funds for the church in the vast Louisiana diocese.

He returned with five priests—including several Lazarists from Rome, among whom were Felix de Andreis and Joseph Rosati—and 26 other men from Italy and France—including Antoine Blanc—who intended to become priests or brothers.

In order to be able to train priests at home, rather than rely on a European missionaries, he established St. Mary's of the Barrens Seminary in Perryville in 1818,[42] placing it under the charge of the Lazarist fathers.

[53] In August of that year, he also recruited the future saint Rose Philippine Duchesne and her religious order from France, the Society of the Sacred Heart, to open schools for girls on the frontier.

DuBourg visited Washington, D.C. in 1823,[53] where he met the U.S. Secretary of War, John C. Calhoun, who encouraged the Jesuit missions and obtained federal funding for the establishment of Indian schools.

[43] At the time he was installed a bishop, the Diocese of Montauban had 242,000 Catholics, 353 priests, grand churches, seminaries and lay schools, and numerous religious orders operating.