Career
McCarthy was deployed along with his regiment to Puerto Rico where they disembarked on July 25, 1898. McCarthy was mustered out of service on January 21, 1899. McCarthy served as a Democrat to represent Marlborough in the Ninth Middlesex District of the While in the House, McCarthy served on the Mercantile Affairs Committee.
McCarthy served in the Massachusetts State Senate from 1912 to 1914.
In 1916 the Massachusetts legislature and electorate approved the calling of a Constitutional Convention. McCarthy served on the Convention"s committee on Military Affairs.
