Complex sentence: Hostus is best known from the Roman champion, Hostus Hostilius, a companion of Romulus, the founder and first king of Rome, who fell in battle against the Sabines under Titus Tatius in the earliest years of the city.
Split into simpler sentences: Hostus is best known from Hostus Hostilius, a companion of Romulus, the founder and first king of Rome. Hostus was a Roman champion who fell in battle against the Sabines under Titus Tatius in the earliest years of the city.