Srebrenica is still giving up its dead: month after month, more human remains are being found and identified by their DNA. So far, 6974 victims of the massacre have been named, including 136 as the ceremony began.
In all, the International Criminal Tribunal for the former Yugoslavia has placed the final death toll at 7826.
Under the shadow of that tragedy, the commemoration was as tense as it was sorrowful. In the face of great domestic controversy, Vucic chose to attend as a gesture of reconciliation.
Before the ceremony, he wrote an open letter saying: "There are no words to express regret and pain for the victims as well as anger and bitterness towards those who committed that monstrous crime.
"Serbia clearly and unambiguously condemns this horrible crime and is disgusted with all those who took part in it and will continue to bring them to justice."
On this most sensitive of subjects, Vucic chose his words with the utmost care. But survivors noted that he did not use the word "genocide" to describe Srebrenica's tragedy. "Look at those thousands of tombstones: is he not ashamed to say that this was not genocide?" said Hamida Dzanovic, whose husband was among those killed. "Is he not ashamed to come here?" she asked.
When the Serbian leader appeared for the ceremony, an angry crowd stoned his black-clad delegation, causing all of them to run back to their cars. With jeers ringing in his ears, Vucic was forced to leave the occasion, his foreign minister condemning the incident as an attack on Serbia.
So the ceremony focused on remembrance, rather than reconciliation. "All of my family members are here under these tombstones. This cannot be denied," said Kada Hotic, who lost her son and husband in Srebrenica.
Many Bosnian Muslims also remember Vucic's incendiary statement during the Balkan wars that for every dead Serb, 100 Muslims should be killed. Some in the crowd held a banner with the quote to remind him of his past. Vucic, a former ultranationalist, is now a moderate with a pro-Western stance.
Among the dignitaries at the ceremony were Ahmet Davutoglu, the Turkish Prime Minister, Queen Noor of Jordan and the Princess Royal. Particularly significant was the presence of Bill Clinton, who was serving his first term as President when Srebrenica fell. As such, he represented the generation of world leaders who failed to prevent the crime.
Before the ceremony, Clinton uttered words of regret. "I grieve that it took us so long," he said. "I never want to see another killing field like this."
What made Srebrenica's ordeal all the more painful was that outside powers had declared the town a haven at the time. United Nations Resolution 819, passed in 1993, named Srebrenica as a "safe area which should be free from any armed attack or hostile act".
Thousands of refugees, who had been driven from towns and villages across central Bosnia, gathered in Srebrenica before the massacre, hoping that the phrase "safe area" would mean something. Dutch peacekeeping troops had been deployed in the town, although whether they had a mandate, let alone the will or the means to protect civilians was unclear.
- additional reporting AP