The collection of documents started forming in June 1940. The Soviet army occupied Latvia on 17 June 1940, and on 21 June a new government was formed by Moscow's emissary Andrey Vyshinsky. The Communist Party started to operate legally as the only legal political force, with its documentation and archives. It became a regional organisation of the Soviet Communist Party. After the creation of the Institute of Party History in 1945, all archives of the LCP CC were stored in the Party archive, which was a department of the institute. In April 1990, the LCP split into two factions, pro and anti-independence. The anti-independence faction had a majority in the Central Committee, and with the support of the Soviet military, it seized the main buildings and other property of the LCP, including the Institute of Party History and its archive. The LCP actively supported anti-independence actions in Latvia in January 1991, as well as the 1991 August coup in Moscow. After the failure of the coup and the reestablishment of independent Latvia, the LCP was declared illegal on 10 September 1991, as an organisation hostile to the reestablishment of state independence. Its archives were handed over to the Latvian State Archive. The staff of the LCP CC managed to shred some of the operational documents which were not stored in the Party archive, but the documents that were not destroyed were added to the collection. After its acquisition by the Latvian State Archives, the whole collection of files was made fully available to the public.