'Butcher of Bosnia' Ratko Mladic goes on trial over slaughter at Srebrenica ICTY via AFP - Getty Images Former Bosnian Serb army chief Ratko Mladic sits in a courtroom in The Hague on Wednesday as his trial opens. Mladic, 70, faces 11 overall counts for genocide, war crimes and crimes against humanity. THE HAGUE, Netherlands -- Bosnian Serb general Ratko Mladic went on trial for genocide on Wednesday, accused of leading the slaughter of 8,000 unarmed Muslim boys and men in Srebrenica in 1995, Europe's worst atrocity since World War II. The ailing 70-year-old Mladic's appearance at the U.N. tribunal for the former Yugoslavia marks the end of a long wait for justice to survivors of the 1992-95 war that left some 100,000 people dead. Mladic gave a thumbs-up and clapped to supporters in the court's public gallery as the trial got under way. He is accused of 11 charges of genocide, crimes against humanity and war crimes. He allegedly orchestrated not only the week-long massacre in Srebrenica, at the time a U.N. "safe haven," but also the 43-month siege of Sarajevo, in which more than 10,000 people were killed by snipers, machineguns and heavy artillery. Munira Subasic, who lost 22 family members in the 1995 Srebrenica massacre, was among a group of relatives of war dead heading into the courtroom to face Mladic. The 65-year-old said she wanted to look him in the eye "and ask him if he will repent for what he did." Murderer! Mladic, who was arrested last May after 16 years on the run, has dismissed the charges as "monstrous" and says he is too ill to stand trial. The court entered a "not guilty" plea on his behalf. The case has inevitably stirred up violent emotions in the Balkans. Survivors watching proceedings from the court gallery have shouted "Murderer!" and "Killer!" at a man nicknamed the "Butcher of Bosnia." Serge Ligtenberg / Getty Images A career soldier, Mladic stands accused of orchestrating the siege of Sarajevo and the slaughter of 8,000 Muslims in Srebrenica. For his part, Mladic has been angry and defiant during pre-trial hearings, heckling the judge, shouting and interrupting the proceedings. "The whole world knows who I am," he told a hearing last year. I am General Ratko Mladic. I defended my people, my country ... now I am defending myself. Mladic was in charge of the Bosnian Serb army when, over several days in July 1995, Serb fighters overran the Srebrenica enclave in eastern Bosnia, theoretically under the protection of Dutch U.N. peacekeepers. Srebrenica: The story that will never end Video footage shot at the time showed Mladic mingling with Muslim prisoners. Shortly afterwards, the men and boys were separated from the women, stripped of identification, and shot. The dead were bulldozed into mass graves, then later dug up with excavators and hauled away in trucks to be better hidden from the world, in dozens of remote mass graves. War crimes suspect Ratko Mladic made his first appearance before a war crimes tribunal at The Hague. He called the charges against him "obnoxious" and told the court he was "too ill" to face trial. Prosecutors say Mladic was part of a "joint criminal enterprise to eliminate the Bosnian Muslims in Srebrenica by killing the men and boys ... and forcibly removing the women, young children and some elderly men." Mladic is also held responsible for the siege and bombardment of the Bosnian capital Sarajevo, which prosecutors said was intended to "spread terror among the civilian population." The horrors of the siege, together with the Srebrenica massacre, eventually galvanized world opinion in support of the campaign of Western airstrikes on Bosnian Serb targets that brought the conflict to an end shortly after. Mladic was indicted in 1995 along with Radovan Karadzic, the Bosnian Serbs' political leader. Serbian war crimes fugitive Ratko Mladic has been arrested. He was indicted by the International Criminal Tribunal for orchestrating the Srebrenica massacre. He is charged with genocide, crimes against humanity and violations of the laws of war. Yet both remained free in Serbia for more than a decade before being tracked down and sent to The Hague. Karadzic's trial is already under way. Defense lawyers say they have not had enough time to review the huge case file prepared by prosecutors and asked for the trial to be postponed, but the request was denied. 411 witnesses Serge Brammertz, the court's chief prosecutor, has dismissed Mladic's assertion that he is too frail to sit through a 200-hour prosecution case involving testimony from 411 witnesses. His appearance in The Hague is testament to the work of the tribunal, which has defied skeptics by managing, in the course of 19 years, to arrest all its 161 indictees. But some victims still fear that Mladic, who has received physical therapy for a possible stroke, could escape judgment by dying in mid-trial. Mladic's mentor, former Serbian president Slobodan Milosevic, the architect of the Balkan wars, died in detention in 2006, a few months before a verdict in his trial for genocide and other war crimes in Croatia, Bosnia and Kosovo.