Madiun was the site of a noted uprising in 1948 by elements of the Communist Party of Indonesia (PKI), the "Madiun Affair". After the signing of the Renville Agreement that year, guerrilla units and militias under the influence of PKI were ordered to disband. In Madiun a group of PKI militia refused to disarm and were killed in September. The killings sparked a violent uprising. Army sources claimed that the PKI had announced the proclamation of the "Soviet Republic of Indonesia" on 18 September with Musso as its president and Amir Sjarifuddin as its prime minister.
The uprising was suppressed by republican troops. On 30 September, Madiun was taken over by republican troops of the Silwangi Division. Thousands of party cadres were killed and 36,000 were imprisoned. Amongst the executed were several leaders including Musso who was killed on 31 October, allegedly while trying to escape from prison. Other PKI leaders such as D.N. Aidit went into exile in China
