Complex sentence: Wanting to keep things quiet in southern Italy, Napoleon and Ferdinand signed a convention that specified that the French would evacuate Apulia in return for the Kingdom of Naples to stay neutral in the impending War of the Third Coalition.
Split into simpler sentences: Wanting to keep things quiet in southern Italy, Napoleon and Ferdinand signed a convention that specified that the French would evacuate Apulia. In return, the Kingdom of Naples would stay neutral in the impending War of the Third Coalition.