Former president Jiang Zemin completed a historic leadership transition today when he handed over the chairmanship of the Party’s Central Military Commission to Communist Party chief Hu Jintao. The party’s elite Central Committee accepted the resignation of Jiang, 78, on the final day of a four-day closed-door plenum and approved Hu’s rise to Chairman of the party’s decision-making Central Military Commission, Xinhua news agency said. Hu, 61, who replaced Jiang as party chief in 2002 and as president in 2003, now holds the three most powerful positions in China, rounding off the first orderly succession in Chinese Communist history. ‘‘The Hu Jintao era has started,’’ a Chinese political analyst said on condition of anonymity. In a sign that Jiang’s influence is already waning, his closest political ally, Vice President Zeng Qinghong, did not join the Military Commission. Xu Caihou, 61, a member of the Military Commission. Xu Caihou, 61, a member of the Military Commission, was promoted as a Vice-Chairman, Xinhua said. Jiang’s departure is unlikely to result in dramatic changes in domestic, foreign and economic policies with Hu set to continue the market-friendly reforms that transformed China into the world’s seventh-largest economy.