The Federal government's power to end slavery was limited by the Constitution, which before 1865 was understood to reserve the issue to the individual states.
ðə fˈɛdɚɹəl ɡˈʌvɚnmənts pˈaʊɚ tʊ ˈɛnd slˈeɪvɚɹi wʌz lˈɪmɪɾᵻd baɪ ðə kˌɑːnstɪtˈuːʃən, wˌɪtʃ bᵻfˌoːɹ wˈʌn θˈaʊzənd ˈeɪthˈʌndɹɪd sˈɪksti fˈaɪv wʌz ˌʌndɚstˈʊd tə ɹɪzˈɜːv ðɪ ˈɪʃuː tə ðɪ ˌɪndᵻvˈɪdʒuːəl stˈeɪts.