During the Spanish–American War, Cannon served as the lieutenant colonel (i.e., second-in-command) of the 2nd United States Volunteer Cavalry.
dˈʊɹɹɪŋ ðə spˈænɪʃ ɐmˈɛɹɪkən wˈɔːɹ, kˈænən sˈɜːvd æz ðə luːtˈɛnənt kˈɜːnəl ˈaɪ.ˈiː., sˈɛkəndɪŋkəmˈænd ʌvðə sˈɛkənd juːnˈaɪɾᵻd stˈeɪts vˌɑːləntˈɪɹ kˈævəlɹi.