Dred Scott was a slave whose master took him from a slave state to a territory that was free as a result of the Missouri Compromise.
dɹˈɛd skˈɑːt wʌzɐ slˈeɪv hˌuːz mˈæstɚ tˈʊk hˌɪm fɹʌm ɐ slˈeɪv stˈeɪt tʊ ɐ tˈɛɹɪtˌoːɹi ðæt wʌz fɹˈiː æz ɐ ɹɪzˈʌlt ʌvðə mɪzˈʊɹɹi kˈɑːmpɹəmˌaɪz.