While in Foxborough, his health declined to the point where he had to give up his priestly duties.[1] He spent the last four years of his life at his mother's house on Washington Street in Taunton, bedridden with chronic rheumatism, where he died on August 18, 1889.[1]
In June 1867, Brennan purchased a house on High Street and converted it into a rectory.[6][4][5][7] Plans were then made for a new church at this location, and thus the current church was constructed next to the rectory.[8] While in Dedham, he also took care of what is today the St. Catherine's Church in Norwood, Massachusetts,[9] which he improved during his pastorate.[4]
Whatever prejudices may naturally exist against the establishment of a Roman Catholic School in so central a location, the community cannot but feel that the transformation of a building recently used only for the indiscriminate sale of liquors into an institution founded for 'promoting virtue, learning and piety in the town of Dedham' is an object worthy only of the most exalted motives, and in this view should be accepted as a public blessing.[10]
The school held a number of fundraisers,[11] but with the heavy debt of the parish the school closed on June 27, 1879.[11][12][13][14] The closure was intended to be temporary,[13] but it never reopened.[4] The building was sold in 1905.[15]
It was a "somewhat pleasant surprise" when it was announced on January 14, 1877, that Brennan would be leaving St. Mary's and St. Catherine's and that the parish would be turned over to his curate, Dennis J. O'Donovan.[16] Many in the congregation had been unhappy with Brennan. The week before, he became the first priest to ever file for bankruptcy.[16] The parish was also bankrupt at the time.[17]
^Hanson, Robert (March 2005). "The Inn Thing: Taverns of Dedham"(PDF). Dedham Historical Society Newsletter. Deadham, Massachusetts: Dedham Historical Society. Archived from the original(PDF) on April 22, 2021. Retrieved April 10, 2020.
Leahy, William Augustine (1899). "Archdiocese of Boston". History of the Catholic Church in the New England States. By Byrne, William; Leahy, William Augustine; McCoy, J. J.; O'Donnell, James H.; Dowling, Austin; Finen, John E.; Young, Edmund J. A.; Michaud, John S. Vol. 1. Boston: Hurd & Everts Co. pp. 1–350. Retrieved April 10, 2020.