Complex sentence: In 1832, on returning to his residence at Clapham from Dover, he was seized with a dangerous malarial fever, but, though he recovered his health, he was never again able to attend to business or to manage his property.
Split into simpler sentences: In 1832, on returning to his home at Clapham from Dover, he was seized with a dangerous malarial fever. Though he recovered his health, he was never again able to attend to business or to manage his property.