Complex sentence: Returning to England in 1833 he was sent upon a mission in the western district, where he was placed successively at Trelawny, Tawstock, Weobley, Poole, and Cannington.
Split into simpler sentences: Returning to England in 1833 he went at once upon a mission in the western district. He was placed successively at Trelawny, Tawstock, Weobley, Poole, and Cannington.