Complex sentence: After the initial contact with Farnese troops, Mattei's soldiers followed him and were involved in further skirmishes while remaining Papal troops returned to defend Rome A number of other dutchies sided with the Farnese and moved to attack Rome itself; the centre of Papal power.
Split into simpler sentences: After the initial contact with Farnese troops, Mattei's soldiers left the bulk of the papal army and followed him. They were involved in further skirmishes while remaining Papal troops returned to defend Rome A number of other duchies sided with the Farnese and moved to attack Rome itself; the centre of Papal power.