Complex sentence: He was retained in three succeeding elections (49th: February 16,1949; 50th: October 30,1952; and 51st: May 21,1953), and was finally ousted on December 10,1954, when he was replaced by Ichirō Hatoyama.
Split into simpler sentences: He was retained in three succeeding elections (49th: February 16,1949; 50th: October 30,1952; and 51st: May 21,1953). Power slipped away as he was ousted on December 10,1954, when he was replaced by Ichirō Hatoyama.