Gross's tenure in Louisville, however, was not without controversy. His predecessor, Joshua Flint, had become famous as a surgeon in New England before coming to Louisville, and in 1850 Flint accepted a position as chief of surgery in the newly organized Kentucky School of Medicine, a move which began a bitter rivalry between that institution and the Louisville Medical Institute until the two schools were merged in 1908. Gross became very popular in social circles, however. He and his family were close friends with the Crittendens, Breckenridges, Wooleys, Prestons, Wickliffes, Pirtles, Ballards, Rowans, Guthries, and Prentices. Gross had even been a guest of Henry Clay at his estate, "Ashland," in Lexington. He was a member of the Unitarian Church and the St. George Lodge of Masons. In 1854, he also became a member of the American Philosophical Society. In August 1855, Gross, a close friend of John Barbee, the Mayor of Louisville, helped save the Catholic Cathedral on Fifth Street from an anti-foreign Know-Nothing Party mob that intended to burn it down in what was known as the Bloody Monday riot.