The Forest Brothers, also known as Brothers of the Forest, Forest Brethren, or Forest Brotherhood, were Estonian, Latvian, and Lithuanian partisans who waged a guerrilla war against Soviet rule during the Soviet invasion and occupation of the three Baltic states during, and after, World War II. Similar anti-Soviet Eastern European resistance groups fought against Soviet and communist rule in Bulgaria, Poland, Romania, and western Ukraine.
The Soviet Red Army occupied the independent Baltic states in 1940–1941 and, after a period of German occupation, again in 1944–1945. As Stalinist repression intensified, 50,000 residents of these countries used the heavily forested countryside as a natural refuge and base for armed anti-Soviet resistance. Resistance units varied in size and composition, ranging from individually operating guerrillas, armed primarily for self-defense, to large and well-organized groups able to engage significant Soviet forces in battle.
By the early 1950s, the Soviet forces had eradicated most of the Forest Brother resistance. Intelligence gathered by the Soviet spies in the West and KGB infiltrators within the resistance movement, in combination with large-scale Soviet operations in 1952 managed to end the campaigns against them. Many of the remaining Forest Brothers laid down their weapons when offered an amnesty by the Soviet authorities after Joseph Stalin's death in 1953, although isolated engagements continued into the 1960s. The last individual guerrillas are known to have remained in hiding and evaded capture into the 1980s, by which time the Baltic states were pressing for independence through peaceful means.