Operation Storm (Serbo-Croatian: Operacija Oluja / ) 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 Biha 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 European land battle since the Second World War. 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 Biha 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 built 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.

The HV's and ARBiH's strategic success was a result of a series of improvements to the armies themselves, and crucial breakthroughs made in the ARSK positions that were subsequently exploited by the HV and the ARBiH. The attack was not immediately successful at all points, but seizing key positions led to the collapse of the ARSK command structure and overall defensive capability. The HV capture of Bosansko Grahovo, just before the operation, and the special police's advance to Graac, made it nearly impossible to defend Knin. In Lika, two guard brigades quickly cut the ARSK-held area which lacked tactical depth and mobile reserve forces, and they isolated pockets of resistance, positioned a mobile force for a decisive northward thrust into the Karlovac Corps area of responsibility (AOR), and pushed ARSK towards Banovina. The defeat of the ARSK at Glina and Petrinja, after a tough defensive, defeated the ARSK Banija Corps as well since its reserve was pinned down by the ARBiH. The RSK relied on the Republika Srpska and Yugoslav militaries as its strategic reserve, but they did not intervene in the battle. The United States also played a role in the operation by directing Croatia to a military consultancy firm, Military Professional Resources Incorporated (MPRI), that signed a Pentagon licensed contract to advise, train and provide intelligence to the Croatian army.

The HV and the special police suffered 174211 killed or missing, while the ARSK had 560 soldiers killed. Four UN peacekeepers were also killed. The HV captured 4,000 prisoners of war. The number of Serb civilian deaths is disputedCroatia claims that 214 were killed, while Serbian sources cite 1,192 civilians killed or missing. The Croatian population had been years prior subjected to ethnic cleansing in the areas held by ARSK by rebel Serb forces, with an estimated 170,000250,000 expelled and hundreds killed. During and after the offensive, around 150,000200,000 Serbs of the area formerly held by the ARSK had fled and a variety of crimes were committed against the remaining civilians there by Croatian forces.

The International Criminal Tribunal for the Former Yugoslavia (ICTY) later tried three Croatian generals charged with war crimes and partaking in a joint criminal enterprise designed to force the Serb population out of Croatia, although all three were ultimately acquitted and the tribunal refuted charges of a criminal enterprise. The ICTY concluded that Operation Storm was not aimed at ethnic persecution, as civilians had not been deliberately targeted. The ICTY stated that Croatian Army and Special Police committed a large number of crimes against the Serb population after the artillery assault, but that the state and military leadership was not responsible for their creation and organizing and that Croatia did not have the specific intent of displacing the country's Serb minority. However, Croatia adopted discriminatory measures to make it increasingly difficult for Serbs to return. Human Rights Watch reported that the vast majority of the abuses during the operation were committed by Croatian forces and that the abuses continued on a large scale for months afterwards, which included summary executions of Serb civilians and destruction of Serb property. In 2010, Serbia sued Croatia before the International Court of Justice (ICJ), claiming that the offensive constituted a genocide. In 2015, the court ruled that the offensive was not genocidal and affirmed the ICTY's previous findings.

The Yugoslav Wars were a series of separate but related ethnic conflicts, wars of independence, and insurgencies fought in the former Yugoslavia from 1991 to 2001, leading up to and resulting from the breakup of the Yugoslav federation in 1992. Its constituent republics declared independence due to unresolved tensions between ethnic minorities in the new countries, which fueled the wars. Most of the wars ended through peace accords, involving full international recognition of new states, but with a massive human cost and economic damage to the region.

During the breakup of Yugoslavia, initially, the Yugoslav People's Army (JNA) sought to preserve the unity of the whole of Yugoslavia by crushing the secessionist governments, but it increasingly came under the influence of the Serbian government of Slobodan Milošević, which evoked Serbian nationalism to replace the weakening communist system. As a result, the JNA began to lose Slovenes, Croats, Kosovo Albanians, Bosniaks, and Macedonians, and as a result, it effectively became a Serb army. According to a 1994 United Nations report, the Serb side did not aim to restore Yugoslavia; instead, it aimed to create a "Greater Serbia" from parts of Croatia and Bosnia. Other irredentist movements have also been brought into connection with the wars, such as "Greater Albania" (from Kosovo, though it was abandoned following international diplomacy) and "Greater Croatia" (from parts of Herzegovina, until 1994 when the Washington Agreement ended it).Often described as Europe's deadliest conflicts since World War II, the wars were marked by many war crimes, including genocide, crimes against humanity, ethnic cleansing and rape. The Bosnian genocide was the first European crime to be formally classified as genocidal in character since World War II, and many key individuals who perpetrated it were subsequently charged with war crimes. The International Criminal Tribunal for the former Yugoslavia (ICTY) was established by the UN to prosecute these crimes. According to the International Center for Transitional Justice, the Yugoslav Wars resulted in the deaths of 140,000 people, while the Humanitarian Law Center estimates at least 130,000 people who died. The conflicts resulted in major refugee and humanitarian crises.