In line with the Split Agreement signed between Tuđman and Izetbegović on 22 July, a joint military offensive by the HV and the HVO codenamed Operation Summer '95 took place in western Bosnia. The HV-HVO force gained control of Glamoč and Bosansko Grahovo and isolated Knin from Republika Srpska. On 4 August, the HV launched Operation Storm that effectively dissolved the Republic of Serbian Krajina. With this, the Bosniak-Croat alliance gained the initiative in the war, taking much of western Bosnia from the VRS in several operations in September and October. The first one, Operation Una, began on 18 September 1995, when HV crossed the Una river and entered Bosnia. In 2006, Croatian authorities began investigating allegations of war crimes committed during this operation, specifically the killing of 40 civilians in the Bosanska Dubica area by troops of the 1st Battalion of the 2nd Guards Brigade.