Apollo's role as the slayer of the Python led to his association with battle and victory; hence it became the Roman custom for a paean to be sung by an army on the march and before entering into battle, when a fleet left the harbour, and also after a victory had been won.
ɐpˈɑːloʊz ɹˈoʊl æz ðə slˈeɪɚɹ ʌvðə pˈaɪθən lˈɛd tə hɪz ɐsˌoʊsɪˈeɪʃən wɪð bˈæɾəl ænd vˈɪktɚɹi; hˈɛns ɪt bɪkˌeɪm ðə ɹˈoʊmən kˈʌstəm fɚɹə pˈiːən təbi sˈʌŋ baɪ ɐn ˈɑːɹmi ɔnðə mˈɑːɹtʃ ænd bᵻfˌoːɹ ˈɛntɚɹɪŋ ˌɪntʊ bˈæɾəl, wˌɛn ɐ flˈiːt lˈɛft ðə hˈɑːɹbɚ, ænd ˈɔːlsoʊ ˈæftɚɹ ɐ vˈɪktɚɹi hɐdbɪn wˈʌn.