Following the death of Mao in September 1976 and the coup d'état against the radical Gang of Four a month later, Chen became increasingly active in the country's political life. He and General Wang Zhen petitioned Party chairman Hua Guofeng to rehabilitate Deng Xiaoping at the March 1977 CPC CC Work Conference, but were turned down. After Deng was rehabilitated later that year, Chen led the attack on the Maoist era at the November–December 1978 CPC CC Work Conference, raising the sensitive "six issues": the purges of Bo Yibo, Tao Zhu, Wang Heshou and Peng Dehuai; the 1976 Tiananmen Incident; and, Kang Sheng's errors. Chen raised the six issues in order to undermine Hua and his leftist supporters. Chen's intervention tipped the balance in favor of movement toward an open repudiation of the Cultural Revolution and Deng Xiaoping's promotion, in December 1978, to de facto head of the regime. Chen laid the basis for Deng's "reform and opening" program.