Complex sentence: In 1862, during the American Civil War, he moved to Europe, and worked primarily in London and Paris, and from 1863 to 1866, served as surgeon to Empress Eugénie.
Split into simpler sentences: In 1862, during the American Civil War, he moved to Europe and worked primarily in London and Paris. From 1863 to 1866, he served as surgeon to Empress Eugénie.