Complex sentence: He had considerable success in the United States and England in the early 1950s, but by 1953, de Staël's depression led him to seek isolation in the south of France (eventually in Antibes), and he committed suicide in 1955.
Split into simpler sentences: He had considerable success in the United States, and England in the early 1950s. But by 1953, de Staël's depression led him to seek isolation in the south of France (eventually in Antibes), and he committed suicide in 1955.