March
The Soviet troops invaded the Zhenbao Island situated on the Chinese side of the main channel of the Wusuli River, provoking a serious incident of bloodshed. China’s border troops were forced to fight back in self-defense.
April 1–24
The 9th CPC National Congress was convened. It confirmed the “theory of continued revolution under the dictatorship of the proletariat” and legitimized the erroneous theory and practice of the “Cultural Revolution.” The ideological, political and organizational guidelines of the 9th Congress were utterly wrong.
April 28
The 1st Plenary Session of the 9th CPC Central Committee elected Mao Zedong chairman, and Lin Biao vice-chairman of the Central Committee. The 1st Meeting of the Political Bureau of the 9th CPC Central Committee approved the list of the CPC Central Military Commission, with Mao Zedong elected chairman.
September 23
China successfully conducted its first underground nuclear test.
October 1
China’s first subway line—the first phase of the Beijing Subway, was completed and put into operation.
October 7
China’s first self-developed full-automatic long-distance telephone equipment was successfully manufactured, according to the Xinhua News Agency.
From: Chronicle of the People's Republic of China (October 1949 — September 2019) ,edited by The Institute of Party History and Literature of the Central Committee of the Communist Party of China, PP72-73