θˈoːɹnbɜːɡ wʌz ɐpˈɔɪntᵻd ɐtˈɜːni dʒˈɛnɚɹəl ʌvðə θˈɜːd dʒuːdˈɪʃəl sˈɜːkɪt ʌv tˌɛnəsˈiː ɪn wˈʌn θˈaʊzənd ˈeɪthˈʌndɹɪd sˈɪksti sˈɪks, ænd wʌz ᵻlˈɛktᵻd tə ðɪs ˈɑːfɪs ɪn wˈʌn θˈaʊzənd ˈeɪthˈʌndɹɪd sˈɪksti ˈeɪt ænd wˈʌn θˈaʊzənd ˈeɪthˈʌndɹɪd sˈɛvənti.
Thornburgh was appointed attorney general of the third judicial circuit of Tennessee in 1866, and was elected to this office in 1868 and 1870.