Complex sentence: In March 1933, Chen Geng was sent to Shanghai to have better medical treatment of his leg wounds, but he was captured by Kuomintang, however, because he had saved life of Chiang Kai-shek-Kuomintang's leader, his life was spared.
Split into simpler sentences: In March 1933, Chen Geng was sent to Shanghai to have better medical treatment of his leg wounds, but he was captured by Kuomintang. However, as he had saved the life of Chiang Kai-shek-Kuomintang leader, his life was spared.