 On July 1, 1916, he knocked out Alfred "Soldier" Kearns in the eighth round at the Averne Athletic Club in Queens, New York.Kearns was considered a strong puncher though Brennan possessed a two-inch advantage in reach.On July 15, 1916, he defeated Joe Cox in a ten-round newspaper decision of the "Brooklyn Daily Eagle" at the Broadway Arena in Brooklyn, New York.