Gwardia Ludowa or GL was a communist underground armed organization created by the communist Polish Workers' Party in German-occupied Poland, with sponsorship from the Soviet Union. Formed in early 1942, within a short time Gwardia Ludowa became the largest clandestine fighting force on Polish soil which refused to join the structures of the Polish Underground State loyal to the London-based government-in-exile. In the January 1 of 1944 GL was incorporated into the communist Armia Ludowa.

The Polish Underground State [a] was a single political and military entity formed by the union of resistance organizations in occupied Poland that were loyal to the Government of the Republic of Poland in exile in London. The first elements of the Underground State were established in the final days of the German and Soviet invasion of Poland, in late September 1939. The Underground State was perceived by supporters as a legal continuation of the pre-war Republic of Poland that waged an armed struggle against the country's occupying powers: Nazi Germany and the Soviet Union. The Underground State encompassed not only military resistance, one of the largest in the world,[b] but also civilian structures, such as justice, education, culture and social services.