The Holy Cross Mountains Brigade was the only Polish partisan unit during World War II, which as a partisan unit liberated prisoners of a concentration camp outside Polish territories, namely, a women's camp in Holýšov, a sub-camp of KL Flossenburg, in which over 1000 women of various nationalities were imprisoned.

The Holy Cross Mountains Brigade of the National Armed Forces was one of the largest partisan formations operating on Polish territory. Its soldiers fought simultaneously against the German occupiers and the communist underground, the latter not recognizing the legal Polish authorities in exile and constituting the forefront of the new Soviet occupation. Thanks to a happy coincidence and skillful diplomacy of the commanders, the whole unit managed to get to the West, avoiding internal breakdown by neither the Wehrmacht, the Waffen SS, nor the Red Army. It was also the only unit of the Polish independence underground which established tactical contact with the forces of the Western Allies, joined them and cooperated tactically in the fight against Germany in the last days of World War II.

The unit was established on 11 August 1944 in the Lasocin estate. The Brigade conducted activities against the Germans. They were, however, limited in nature and consisted of self-defense, the protection of the local population against repression and pacification activities, as well as the supply of weapons and military materials. The soldiers of the National Armed Forces fought several dozen battles and skirmishes against the gendarmerie, the Wehrmacht (including the Luftwaffe), as well as collaborative formations: the Ukrainian Schutzmannschaft and the Turkestan Ostlegionen. During one of the battles (27 August 1944), the Brigade fought against a reconnaissance unit of the Ostlegionen which was  supported by an armored train. A month later, on 20 September, in the proximity of Cacow, the Brigade fought a battle against a German unit composed of about 400 Luftwaffe soldiers and around 100 gendarmes. The Holy Cross Mountains Brigade also carried out activities against communist units that were, in fact, Soviet agents. In the whole of the Brigade’s history, there has not been a single case of its soldiers murdering Polish Jews due to their ethnic origin. It should also be noted that Poles of Jewish origin served in the ranks of this formation. 

In January 1945, in the face of the Soviet offensive, the Brigade's command, fearing the approaching Red Army and the NKVD, attempted to retreat West and save the unit as a force capable of fighting for free Poland. Thanks to local, improvised and tactical agreements with German units, the Brigade began marching westward towards the Allied forces. During the march, the Commander of the Brigade did not agree to subordination and military cooperation with Germany. He also did not allow the disarmament of the unit. Ultimately, it was sent to the Czech Republic and left without further orders. During the march, the unit managed to establish contacts with the Czech underground. At the same time, emissaries were sent to the headquarters of the Supreme Commander and Allied troops.

The Holy Cross Mountains Brigade was the only Polish partisan unit during World War II, which as a partisan unit, liberated prisoners of a concentration camp outside Polish territories. It was a women's camp in Holýšov, a sub-camp of KL Flossenburg, in which over 1000 women of various nationalities were imprisoned. The attack of the Polish unit on the camp complex saved the lives of Hungarian Jewish women which the German camp personnel intended to burn alive. Then, the Brigade established tactical contact with units of General George Patton’s Third American Army. In a ceremonial speech to his men, Colonel Antoni Szacki, "Bohun Dąbrowski" (commander of the unit), wrote: "Today our banners are fluttering alongside the victorious American colors, alongside the banners of the liberated Czech nation. Providence has allowed us once again to take part in the fight against the eternal enemy and to contribute  to the joint effort of united nations. In this moment so memorable for us, I thank you for the trust you have given me. Your trust has enabled me to fulfill most of the tasks that we have set ourselves. " 
The Americans investigated the Polish unit in terms of counterintelligence, considering it as a non-German unit, but an allied unit. The Brigade was the only Polish unit granted the right to wear badges of American units and to carry weapons in May 1945. American stars, the head of a native American and symbols of American divisions are visible on photographs.
After the end of the war, the unit was inspected by representatives of the Supreme Commander, and its soldiers and officers were trained in the II Corps of General Anders. In view of the pressure on the part of the Soviets, who unlawfully demanded the handing over of the Polish unit, the American army caused the dissolution of the unit and the creation of units supporting US occupation forces in Germany (Polish Guard Companies).

After the end of the war, the unit was inspected by representatives of the Supreme Commander, and its soldiers and officers were trained in the Polish II Corps commanded by General Anders. In view of the pressure on the part of the Soviets, who unlawfully demanded the handing over of the Polish unit, the American army caused the dissolution of the unit and the creation of units supporting US occupation forces in Germany (Polish Guard Companies).