Born in Lesina in the Austria Empire (now Hvar, Croatia), Mazzanovich immigrated with his family to the United States in 1868. In January 1870, he joined the Army as a musician. Three years later, at the request of his father, he was discharged to help support his family. He returned to the Army in 1881 and served with the cavalry in Arizona. In July 1882, Mazzanovich was honorably discharged. He then worked as a mule-packer and scout during the Army’s final campaign against the Apache.