1944 Polish resistance units were attacked by the Lithuanian Territorial Defense Force under General Povilas Plechavičius. Krzyżanowski attempted to negotiate, but Plechavičius demanded that AK and all Polish partisans were to retreat from the Vilnius region or accept Lithuanian sovereignty over that territory. Krzyżanowski would not agree to such a withdrawal and the fighting escalated, eventually culminating in the Polish victory over the Lithuanian collaborationist forces in the battle of Murowana Oszmianka of May 13-May 14. After that battle Krzyżanowski attempted to resume negotiations but was ignored by the Lithuanian side. The increasing hostilities culminated in June, when Lithuanian pro-Nazi Lithuanian Security Police forces, which had recently suffered a loss of several members in a skirmish with AK, massacred 37 Polish civilians in Glinciszki, a village known to support the Polish partisans. Krzyżanowski ordered his forces to increase the activity against the Lithuanians in retribution and, according to the accounts published in Lithuania, his forces conducted a multitude of actions against the Lithuanian civil population. It is unclear whether he was aware of the Dubingiai incident, in which an AK unit massacred a number of Lithuanian civilians (the estimated number of victims vary between 27 and close to a hundred or more). Although the Armia Krajowa's actions are still controversial in Lithuania, a Lithuanian historian Arunas Bubnys has stated that there were no mass murders by the AK (the only exception being Dubingiai), but that the AK was guilty only of some war crimes against individuals or selected families. He also noted that accusations of genocide or widespread activities by the AK are false and have underlying political motives, including to counteract accusations of widespread German-Lithuanian collaboration and crimes committed by units such as the Lithuanian Security Police. Operation Tempest Beginning in the spring of 1944, the Polish underground was preparing for Operation Tempest, which was designed to cause a large scale uprising behind the German lines to prevent the Soviet takeover of the territory by establishing a local Polish administration before the Soviet's arrival, as a sign to the entire world that the Polish government in exile commanded significant Polish forces. Operation Tempest would also support the Soviet Eastern Front offensive. In June Krzyżanowski and his subordinates prepared Operation Ostra Brama. On 2 July 1944, he gave orders to begin the operation on the 7 July, although because of the Soviet quick advance the operation was put into effect