Complex sentence: Charles swept away any resistance in Italy and soon forced the Neapolitans to sign a treaty of peace; the latter was dealt by Trivulzio, who in the meantime had been named commander-in-chief of the Neapolitan army.
Split into simpler sentences: Charles swept away any resistance in Italy and soon forced the Neapolitans to sign a treaty of peace. The treaty was negotiated by Trivulzio, who in the meantime had been named commander-in-chief of the Neapolitan army.