"t."Besides the Home Army there were other major underground fighting formations: Bataliony Chłopskie, National Armed Forces (NSZ) and Gwardia Ludowa (later Armia Ludowa). From 1943, the leaders of the nationalistic NSZ collaborated with Nazi Germany in a case unique in occupied Poland. The NSZ conducted an anti-communist civil war. Before the arrival of the Soviets, the NSZ's Holy Cross Mountains Brigade left Poland under the protection of the German army. According to the historians Czesław Brzoza and Andrzej Leon Sowa, participation figures given for the underground resistance are often inflated. In the spring of 1944, the time of the most extensive involvement of the underground organizations, there were most likely considerably fewer than 500,000 military and civilian personnel participating, over the entire spectrum, from the right wing to the communists.