It did not obey orders to merge with the Home Army in 1944 and was a part of the Military Organization Lizard Union faction, related to the National Radical Camp political party.

They were critical in respect to the democratic traditions of the SN and in April 1934 gave rise to the splinter National Radical Camp (Obóz Narodowo Radykalny, ONR).

The ONR "ABC" promoted an extreme "social-national" ideology, which included the call for expulsion of the ethnic minorities in Poland, specifically in the Kresy macro-region[3] especially the Germans, Lithuanians, Belarusians, Ukrainians and Jews, and allowing only ethnical Poles who could prove their racial purity up to the fourth generation back (cultural assimilation was excluded) in state leadership positions.

At the time of the formal Polish-Soviet alliance (1941–43), the "NSZ Declaration" equally considered Nazi Germany and the Soviet Union enemies and stressed the organization's determination to fight communist attempts to establish their rule in Poland.

[1] Lacking a large military unit, the nationalists issued on 11 August 1944 an order establishing the Holy Cross Mountains Brigade.

The formation fought most of all against the Soviet NKVD forces, the Polish communist partisans of the People's Army (at Fanisławice and Borów)[5] and the partisans of other Polish non-communist resistance movement military organizations, such as the Home Army (AK), the Peasant Battalions (BCh) and the actual National Armed Forces (NSZ) that maintaining internal organizational autonomy merged with the AK in April 1944.

[2][1] Although the brigade occasionally fought also against the Germans (among others at Brzeście, Zagnańsk, Caców, and Marcinkowice), it avoided confrontations with the occupier and stressed a "clearing of the Polish territories", not only of "red banditry" (i.e. communists), but also of "their fifth column", which from the point of view of this formation included all Polish political trends standing to the left of the Szaniec faction, such as socialists, peasant movement, Christian democrats and even pro-democratic nationalists.

They stood against democracy in any form because of its supposedly "Judeo-Masonic origin", striving to the establishment in Poland the rule of one ideology and one "national" organization, i.e., to put it bluntly, a fascist, totalitarian dictatorship.

[2] The brigade's major success was its defeat of a joint People's Army and Soviet partisans force in a battle fought on 8 September 1944 near Rząbiec.

[6] In individual actions units of the brigade killed several hundred members and sympathizers of the PPR and the AL, in what one historian, Rafał Wnuk, described as a bloody and brutal civil war fought between communists and nationalists in the Kielce province.

[1] As the Soviet Red Army approached Poland, the leaders of the NSZ-ONR decided to evacuate the brigade to the territories controlled by the Western Allies.

As a result, the commanders of the brigade agreed to a limited plan whereby small units of the force were to cross or be parachuted by the Germans back into Poland in order to carry out intelligence work and possibly sabotage at the rear of the advancing Red Army.

According to the historian Rafał Wnuk, the brigade command dispatched about one hundred men to the German intelligence Abwehr training center, from where most of them were sent or were in process of being sent to Poland for anti-Soviet diversionary activities.

[10] Documents uncovered in the German Federal Archives in Koblenz contain correspondence between the Gestapo and the NSZ-ONR indicating close collaboration as far as tracking Jews was concerned.

For collaborating with the German occupier, betraying him or eliminating real and imaginary communists and hiding Jews, he was sentenced to death by the court at the NSZ Headquarters,[16] which he managed to avoid.

When there was a split in the NSZ and the Holy Cross Mountains Brigade was beginning to be formed, he established contact with it, which, despite knowing about him, accepted him into its ranks.

[19] Their liquidation was intended for the political base of the Brigade originating from the ONR to take over full power in Poland by way of a coup d'etat and to introduce a fascist dictatorship there.

[21] Representative of the veterans Jan Józef Kasprzyk described the claims of Nazi collaboration as a product of postwar communist propaganda meant to smear the unit's legacy.

[2] As stated in reports by the Polish Home Army, the brigade was well armed and trained and operated in an almost open environment, and its units were resented by the civilian population.

[1] The head of the intelligence service of the Home Army Kielce Inspectorate noted that the cooperation with the Gestapo "was basically open and individual commanders did not hide the fact that they received weapons and ammunition to fight against communism from the occupying authorities".

[23] A report of the commander of the Home Army in the Radom district from 2 January 1945 states: "The clear cooperation with Germans and the plague of the society as a result of the use of props.

[24] The agrarian People's Party (SL), one of the main components of the Underground State, accused the NSZ-ONR and its Holy Cross Mountains Brigade of contacts with and enjoying support of the Germans.

[25] In turn, an internal bulletin intended for local structures of the National Democratic underground, informed: "Due to a number of incidents of collaboration between the NSZ-ONR and the Germans, the headquarters of the NSZ-SN have announced a change of the name of its formation.

They decided that in the face of the entry of the Red Army into Polish lands and the Soviets installing a puppet communist regime, as well as the disintegration of the AK, a new military organization should be established.