Complex sentence: After setting up defences for the city and gathering some 20,000 slaves and herds of cattle from the countryside, they received instructions from Rome that Vulso was to set sail for Rome, taking most of the fleet, including all the transports, with him.
Split into simpler sentences: After setting up defences of the city and gathering some 20,000 slaves and herds of cattle from the countryside, they received instructions from Rome. These stated that Vulso was to set sail for Rome, taking most of the fleet (including all transports) with him.