by Soviet Partisans and the Wehrmacht. By September, the unit was 700 men strong and was officially named the 5th Vilnian Home Army Brigade (5 Wileńska Brygada Armii Krajowej). Łupaszko's unit fought against the German army and SS units in the area of southern Wilno Voivodeship, but was also frequently attacked by the Soviet Partisans paradropped in the area by the Red Army. In April 1944, Zygmunt Szendzielarz was arrested by the Lithuanian police and handed over to the Gestapo. Łupaszko was free in the same month under circumstances that remain unclear. In reprisal actions, his brigade captured several dozen German officials and sent several threatening letters to Gestapo but it remains unknown if and how these contributed to his release. Dubingiai massacre On 20 June 1944 a Lithuanian unit of the Schutzmannschaft murdered 39 Poles in Glinciszki, including women and children. Lithuanian collaborator units have also harassed civilian Polish population in Pawłów, Adamowszczyzna, and Sieńkowszczyzna. In reprisal, on 23 June 1944, a unit of 5th Vilnian Home Army Brigade attacked the fortified village of Dubingiai, capturing a bunker defended by Lithuanian policemen. The order to attack the village was given by Szendzielarz. Dubingiai became the target of the attack due to many of the policemen, and their families, responsible for the Glinciszki crime living there. Having the list of people who collaborated with the occupier, the Poles began action to avenge the death of the residents of Glinciszki. According to historian Paweł Rokicki, the actions in Dubingiai are a war crime, and the deaths of the civilians were intentional. In Dubingiai between 21 and 27 inhabitants of the village died, including women and children. Operation Ostra Brama In August, the commander of all Home Army units in the Wilno area, Gen. Aleksander "Wilk" Krzyżanowski, ordered all six brigades under his command to prepare for Operation Tempest — a planned all-national rising against the German forces occupying Poland. In what became known as Operation Ostra Brama, Brigade V was to attack the Wilno suburb of Zwierzyniec in cooperation with advancing units of the 3rd Belorussian Front. However, Łupaszko, for fear of being arrested with his units by the NKVD and killed on the spot, disobeyed orders and moved his unit to central Poland. Wilno was liberated by Polish and Soviet forces, and the Polish commander was then arrested by the Soviets and the majority of his men were sent to