Complex sentence: The Cubans hated Kennedy because he failed to fully support them in the Bay of Pigs Invasion; the Mafia hated the Kennedys because, as Attorney General, the young and idealistic Robert Kennedy conducted an unprecedented legal assault on organized crime.
Split into simpler sentences: The Cubans hated Kennedy because he failed to fully support them in the Bay of Pigs Invasion. The Mafia hated the Kennedys because, as Attorney General, the young and idealistic Robert Kennedy conducted an unprecedented legal assault on organized crime.