Much of the population was in deep economic misery, and the level of religious knowledge, after the destruction of church institutions which had been built up over centuries, was dismal.

In October 1839, one of the founders of the Society, Charles Auguste Marie Joseph, Count of Forbin-Janson, the exiled Bishop of Nancy in France, arrived in New York City to start a nationwide preaching tour for which he had been authorized by Pope Gregory XVI.

Meanwhile, with the help of another significant donation from his personal funds, the Fathers of Mercy acquired the newly founded Spring Hill College from the Diocese of Mobile in Alabama.

Two years later, John Hughes, the Archbishop of New York, invited these priests to come from Alabama to his diocese to serve the French-speaking immigrants who were flocking to the city, in the church built by the French bishop.

Lafont was also a strong supporter of the rights of the African-American community of the city, who suffered discrimination even from the few Catholic churches then open.

Services at the Church of St. Vincent de Paul were integrated from the start, as was the parish school, the first in the Northern States to teach students regardless of race.

Around 1856 the parish made the decision to move to the Chelsea neighborhood of the city, where many French residents had settled, drawn there by the developing industrialization in the area.

In 1910 a large bequest was left to the parish to build the Church of Notre Dame, located in the Morningside Heights neighborhood of the borough, in order to promote devotion to Our Lady of Lourdes.

Photographs of the D-Day noon mass at St. Vincent de Paul and the many French exiles and French soldiers who attended the mass may be viewed at Flashbak.com Photos Of New Yorkers After Learning About The D-Day Invasion – June 6, 1944 https://flashbak.com/photos-of-new-yorkers-after-learning-about-the-d-day-invasion-june-6-1944-381282/ The church was re-dedicated after World War II, with President Charles de Gaulle of France present.

The parish maintained a weekly Mass in French since its founding, serving an array of immigrants to the city from various French-speaking countries of the world, representing some 65 nations.

In January 2016, the Apostolic Signatura in Rome, the highest Vatican court, issued its final decision declining to consider the parishioners' appeal.

In addition to providing social services to immigrants from both Europe and Africa, it has been a notable cultural center for the French-speaking.