Complex sentence: However, before hostilities break out, the Trojans tell the Romans of the disappearance of Morbus's statue, and, greatly concerned by this news, the Romans call a meeting of all four races.
Split into simpler sentences: However, before that attack comes, the Trojans tell the Romans of the disappearance of Morbus's statue. Greatly concerned by the disappearance of the statue, the Romans call a counsel with all four races.