Complex sentence: In 1863 his failing health, made worse by his hard work and extended exposure to the damp and draughts of churches, induced him again to visit Italy where he died of smallpox at Rome on the 21st of March 1864.
Split into simpler sentences: In 1863 his failing health, rendered worse by incessant toil and exposure to the damp and draughts of churches, induced him again to visit Italy. He died of smallpox at Rome on the 21st of March 1864.