He was town clerk for Manitowoc in 1857, and was elected Register of Deeds for Manitowoc County in 1858 and 1860. He was elected State Treasurer of Manitowoc County in 1866 and 1868. In 1868, Baetz was a delegate to the Republican National Convention in Chicago that nominated Ulysses S. Grant for President of the United States. He was elected State Treasurer of Wisconsin in 1869 alongside fellow Gettysburg veteran, Governor Lucius Fairchild, and was re-elected in 1871. He did not seek re-election in 1873. He moved to Milwaukee in 1875 and was the first chief librarian for the Milwaukee Public Library from 1878 to 1880. He returned to state office in 1880 and served as Secretary of the State Board of Immigration from 1880 to 1883.