Thanks Dan. I posted this on the SARA site (Spanish Artillery Research Associates) and another member there, Miguel Hernandez, found this info on the howitzer:
"Bronze Howitzer, mounted on granite base, near south end of Military Park, was part of the armament of Morro Castle, Santiago Harbor, Cuba, captured by the United States forces July 2, 1898. Cannon presented to Newark in 1899. Bronze tablet on pedestal gives history of the piece, which was made from older Spanish cannon."
Source: "OFFICIAL GUIDE AND MANUAL of the 250th Anniversary Celebration of the Founding of Newark, New Jersey" Henry Eddington, editor. Page 24 (1916)