On July 11, 1995, more than 8,000 Bosnian Muslim men and boys were slaughtered by Bosnian Serb forces in Srebrenica, an enclave declared a "safe area" by the United Nations and protected by U.N. peacekeepers.
The slaughter is considered Europe's worst massacre since the end of World War II.
The Bosnian Serb troops that perpetrated the massacre were led by Gen. Ratko Mladic, who was arrested in Serbia on Thursday, and will now face war crimes charges that include genocide for his role in Bosnia's 1992-1995 war.
Serb troops under Mladic's command laid siege to the eastern town of Srebrenica at the start of the war. The town's prewar population of 35,000 of mainly Muslim Bosniaks nearly doubled as many more villagers from the outlying areas poured in.
The enclave, which is close to the border with Serbia and surrounded by high, dense mountains, endured constant attacks.
The U.N. Security Council declared Srebrenica a "safe area" in April 1993, a month after the top commander of the U.N. peacekeeping force in Bosnia, French General Philippe Morillon promised those trapped inside the enclave that they would be under U.N. protection.
Despite this, the attacks continued and a Security Council mission that visited Srebrenica two years before the slaughter reported that the Serb troops were perpetrating "a slow-motion process of genocide."
In July 1995, Mladic's troops started another large-scale attack on the town. Realizing that the town would be overrun, thousands of residents swarmed a U.N. military base where hundreds of Dutch peacekeepers were based.
The Dutch peacekeepers, outnumbered and outgunned, allowed the Serb forces to take away thousands seeking refuge inside their base, after Mladic promised they would not be harmed.
The troops separated men and women. The women were put on buses and sent to Bosnian government-held territory. The men and boys were systematically executed in the nearby woods and fields over several days, their bodies buried in mass graves.