The Lithuanian Soviet Socialist Republic (LSSR) was a short-lived Soviet republic declared on December 16, 1918 by a provisional revolutionary government led by Vincas Mickevičius-Kapsukas. It ceased to exist on February 27, 1919 when it was merged with the Socialist Soviet Republic of Byelorussia to form the Lithuanian–Byelorussian Soviet Socialist Republic (Litbel). While efforts were made to represent the LSSR as a product of a socialist revolution supported by local residents, it was largely a Moscow-orchestrated entity created to justify the Lithuanian–Soviet War. As a Soviet historian, adhering to official propaganda, put it: "The fact that the Government of Soviet Russia recognized a young Soviet Lithuanian Republic unmasked the lie of the USA and British imperialists that Soviet Russia allegedly sought rapacious aims with regard to the Baltic countries." Lithuanians generally did not support Soviet causes and rallied for their own national state, declared independent on February 16, 1918, by the Council of Lithuania.

Germany had lost World War I and signed the Compiègne Armistice on November 11, 1918. Its military forces then started retreating from the former Ober Ost territories. Two days later, the government of the Soviet Russia renounced the Treaty of Brest-Litovsk, which had assured Lithuania's independence. Soviet forces then launched a westward offensive against Estonia, Latvia, Lithuania, Poland and Ukraine in an effort to spread the global proletarian revolution and replace national independence movements with Soviet republics. Their forces followed retreating German troops and reached Lithuania by the end of December 1918.

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