In November 1808, he was sent with Anthony Kohlmann to minister to the Catholics of New York City, where they were put in charge of St. Peter's Church, the only Catholic church in the city.
He assisted in establishing the New York Literary Institution, the second Jesuit school in New York City.
As an offshoot of Georgetown College, the institution was staffed by four Jesuit scholastics from Georgetown, with Fenwick as president.
The school was opened in 1808, in a house on Mulberry Street, across the street from the original St. Patrick's Cathedral.
It remained there only briefly, before relocating to Broadway in September 1809; it moved again in March 1810 to a plot of land "far out in the country," north of the New York City limits.
This new site would eventually become the location of the new St. Patrick's Cathedral, in Midtown Manhattan.

The school grew quickly, enrolling the sons of several prominent Catholic and Protestant families, and its curriculum emphasized the study of Latin, Ancient Greek, and French.
However, the Jesuit superior in the United States, Giovanni Antonio Grassi, determined that there were not enough Jesuits in the United States could not sustain both Georgetown and the New York Literary Institution.
Despite Kohlmann desiring to close Georgetown, Grassi sided with the bulk of Jesuits who were native to Maryland and ordered the New York school closed in 1813, with it officially shuttering in April 1814.
Responsibility for the facility was transferred to the Trappist order.

While in New York, Fenwick and Kohlmann were called for by the dying Thomas Paine, to his house in Greenwich Village.
Having been unsuccessfully treated by several physicians, Paine sought to priests to heal him.
They attempted to convince him to renounce a lifetime of writings denouncing Christianity, to which he angrily dismissed them from his house.

Fenwick served alongside Kohlmann as pastor of Old St. Patrick's Cathedral in 1809, an office he held until 1815.
When Kohlmann was recalled to Maryland in 1815, Fenwick succeeded him as pastor of St. Peter's Church as well.
He also replaced Kohlmann as the apostolic administrator of the Diocese of New York.
He was successful in prompting hundreds of conversions to Catholicism throughout the diocese during his tenure.
Fenwick was present at the formal dedication of Old St. Patrick's Cathedral in 1816.
He also drew up designs for the new St. Patrick's Cathedral, whose construction would be completed after he left New York.
The Dominican priest, Charles Ffrench, succeeded Fenwick as pastor of St. Peter's, and John Power would become the next pastor of Old St. Peter's in 1825.
Fenwick became vicar general of the diocese for Bishop John Connelly in 1816, in which post he remained until April 1817.
In November 1808, he was sent with Anthony Kohlmann to minister to the Catholics of New York City, where they were put in charge of St. Peter's Church, the only Catholic church in the city. He assisted in establishing the New York Literary Institution, the second Jesuit school in New York City. As an offshoot of Georgetown College, the institution was staffed by four Jesuit scholastics from Georgetown, with Fenwick as president. The school was opened in 1808, in a house on Mulberry Street, across the street from the original St. Patrick's Cathedral. It remained there only briefly, before relocating to Broadway in September 1809; it moved again in March 1810 to a plot of land "far out in the country," north of the New York City limits. This new site would eventually become the location of the new St. Patrick's Cathedral, in Midtown Manhattan.
The school grew quickly, enrolling the sons of several prominent Catholic and Protestant families, and its curriculum emphasized the study of Latin, Ancient Greek, and French. However, the Jesuit superior in the United States, Giovanni Antonio Grassi, determined that there were not enough Jesuits in the United States could not sustain both Georgetown and the New York Literary Institution. Despite Kohlmann desiring to close Georgetown, Grassi sided with the bulk of Jesuits who were native to Maryland and ordered the New York school closed in 1813, with it officially shuttering in April 1814. Responsibility for the facility was transferred to the Trappist order.
While in New York, Fenwick and Kohlmann were called for by the dying Thomas Paine, to his house in Greenwich Village. Having been unsuccessfully treated by several physicians, Paine sought to priests to heal him. They attempted to convince him to renounce a lifetime of writings denouncing Christianity, to which he angrily dismissed them from his house.
Fenwick served alongside Kohlmann as pastor of Old St. Patrick's Cathedral in 1809, an office he held until 1815. When Kohlmann was recalled to Maryland in 1815, Fenwick succeeded him as pastor of St. Peter's Church as well. He also replaced Kohlmann as the apostolic administrator of the Diocese of New York. He was successful in prompting hundreds of conversions to Catholicism throughout the diocese during his tenure. Fenwick was present at the formal dedication of Old St. Patrick's Cathedral in 1816. He also drew up designs for the new St. Patrick's Cathedral, whose construction would be completed after he left New York. The Dominican priest, Charles Ffrench, succeeded Fenwick as pastor of St. Peter's, and John Power would become the next pastor of Old St. Peter's in 1825. Fenwick became vicar general of the diocese for Bishop John Connelly in 1816, in which post he remained until April 1817.
Benedict Joseph Fenwick