Complex sentence: He showed it was false that most slaves remained loyal to their former masters following emancipation; instead, some slaves did choose to stay with their former owners, but most willingly left their masters behind in order to take control of their own lives.
Split into simpler sentences: He showed it was false that most slaves remained loyal to their former masters following emancipation. Some slaves did choose to stay with their former owners, but most willingly left their masters behind in order to take control of their own lives.