Captain Thomas A. O’Brien was born in 1884 and grew up at 280 Burnside Avenue, just a few blocks away. O’Brien was killed in World War I on October 12, 1918, less than a month before Armistice and the end of the war. On December 1, 1924, the Board of Alderman named this park “to pay tribute to the memory of one who made the supreme sacrifice in the World War”.
O’Brien Oval is located in the historic central Bronx neighborhood of Tremont. This area was farmland when the New York and Harlem Railroad opened a station in 1841. The station soon became the center of the village, which was named Tremont in the 1850s by postmaster Hiram Tarbox. Tremont refers to the presence of three major hills in the area, or three mounts: Claremont, Mount Eden, and Mount Hope; these hills also give their names to three of the many small neighborhoods that comprise the Tremont area.