A native of Ensheim, Rhenish Palatinate, Bavaria, Monsignor Peter Joseph Baltes's family emigrated to the United States in 1833, settling in Oswego, New York. Ordained priest on May 21, 1853. Taking care among others of the construction of St. Peter's Church, which would later become the Cathedral of the Diocese of Belleville, he was appointed as the second bishop of the Diocese of Alton following the demise of Msgr. Henry Damian Juncker, receiving his episcopal consecration on January 23, 1870 from Bishop John Henry Luers.
Long suffering from diseases of the kidneys, bladder and liver, after spending a few months in hospitals at New York and Montreal, he returned to Illinois and, after suffering from an inflammation of the liver, died at age 58.