Fighting Solidarity (Polish: Solidarność Walcząca) was a Polish anti-communist underground organization, founded in June 1982 by Kornel Morawiecki in Wrocław in response to the de-legalization of Solidarity and government repression of the opposition after martial law was declared in 1981. It was one of the most radical splinters of Solidarity.
Morawiecki and Fighting Solidarity activists saw their organization as the successor to the Polish resistance in World War II, hence their symbol merged the Solidarity logo with the Kotwica and crowned Polish eagle (in 1945, the new communist regime removed the crown from the eagle's head on the Polish coat of arms; many among the opposition saw the crown as a symbol of independent, non-communist Poland).
One of the main activities of Fighting Solidarity was information warfare: it printed and distributed many underground newspapers (bibuła). The most well-known of these included "Biuletyn Dolnośląski" (Wrocław), "Solidarność Walcząca" (Poznań) and "Galicja" (Rzeszów). Fighting Solidarity's bibuła were the first printed during the period of martial law, being available the day after martial law was introduced. Fighting Solidarity also tried to actively infiltrate the Polish secret police (Służba Bezpieczeństwa) and to support other anti-communist organizations, including ones in other countries of the Soviet Bloc, even the Soviet Union itself. The Polish secret police found it extremely hard to infiltrate the organization, even though they employed various tactics, including kidnapping Morawiecki's children in an attempt to blackmail him. Despite its reputation for militancy, Fighting Solidarity did not support violence or terrorism.