Operation Storm (Serbo-Croatian: Operacija Oluja / Операција Олуја) was the last major battle of the Croatian War of Independence and a major factor in the outcome of the Bosnian War. It was a decisive victory for the Croatian Army (HV), which attacked across a 630-kilometre (390 mi) front against the self-declared proto-state Republic of Serbian Krajina (RSK), and a strategic victory for the Army of the Republic of Bosnia and Herzegovina (ARBiH). The HV was supported by the Croatian special police advancing from the Velebit Mountain, and the ARBiH located in the Bihać pocket, in the Army of the Republic of Serbian Krajina's (ARSK) rear. The battle, launched to restore Croatian control of 10,400 square kilometres (4,000 square miles) of territory - representing 18.4% of the territory it claimed - and Bosniak control of Western Bosnia, was the largest land battle that took place in Europe between the end of World War II and the 2022 Russian invasion of Ukraine. Operation Storm commenced at dawn on 4 August 1995 and was declared complete on the evening of 7 August, despite significant mopping-up operations against pockets of resistance lasting until 14 August.
Operation Storm was a strategic victory in the Bosnian War, effectively ending the siege of Bihać and placing the HV, Croatian Defence Council (HVO), and the ARBiH in a position to change the military balance of power in Bosnia and Herzegovina through the subsequent Operation Mistral 2. The operation was conceived on HV and HVO advances made during Operation Summer '95, when strategic positions allowing the rapid capture of the RSK capital Knin were gained, and on the continued arming and training of the HV since the beginning of the Croatian War of Independence, when the RSK was created during the Serb Log Revolution and Yugoslav People's Army intervention. The operation itself followed an unsuccessful United Nations (UN) peacekeeping mission and diplomatic efforts to settle the conflict.