Complex sentence: In 1933, France seized the Paracels and Spratlys, announced their annexation, formally included them in French Indochina, and built a couple of weather stations on them, but did not disturb the numerous Chinese fishermen it found there.
Split into simpler sentences: In 1933, France seized the Paracels and Spratlys, announced their annexation, formally included them in French Indochina. They built several weather stations on them, but they did not disturb the numerous Chinese fishermen it found there.