Colonel Fitz, the Austrian officer, had begun his day with a commemoration in the Lion Cemetery on a hillside above the city, where 2,254 Austrian soldiers killed in Bosnia in World War I are buried. The colonel said the ceremony, beneath a large statue of a lion that is one of the many Austro-Hungarian relics in the city, had involved an Austrian military band, and ambassadors and military attachés from nations that were allied with the Austro-Hungarian Empire after it responded to the Sarajevo assassinations by declaring war on Serbia in July 1914.

The colonel noted quietly, and without recrimination, that none of the ambassadors were from the countries that now share common membership in the European Union with Austria, but were the enemies of Austria and its main ally, Germany, in World War I. Those old alliances have been a ghostly presence in the current commemorations, with nations that have long since made an official bonfire of the nationalist furies that impelled the 1914-18 war, and the Second World War in 1939-45, taking carefully calibrated roles in Sarajevo.

An academic conference to debate the causes and consequences of the war became eerily anodyne when scholars from France, Germany, Bosnia, Serbia and Croatia and other European nations fell into a dispute ahead of the gathering about the topics to be discussed and the speakers who would address them. In the end, the program for the conference, held at the Hotel Hollywood in the mainly Serbian town of Ilidza, where the archduke and his wife spent their last night before taking a brief train ride into Sarajevo, was devised to avoid any open disputes about the role of Princip or other issues touching on war guilt.

The compromise was guided by the European Union and its diplomatic mission here, which tries to draw rival Bosnian sectarian groups into a less wary and abrasive posture on Bosnia’s future than the main protagonists among the Serbs, Croats and Muslims have shown since the United States-sponsored Dayton agreement that ended the sectarian killing of the 1990s. Peter Sorensen, a Danish diplomat who is the European special representative to Bosnia and Herzegovina, describes his role as that of a referee overseeing a “fierce fight, on a daily basis, over maintaining the political space” allotted to the groups under the Dayton pact.

But Mr. Sorensen and other European diplomats failed to persuade the Bosnian Serb political leaders to join in shared commemorations of the centenary of the Sarajevo assassinations. Instead, Milorad Dodik, the most militant of the Bosnian Serb leaders, led his followers on Friday in erecting a seven-foot statue to Princip in a hardscrabble park in Lukavica, a suburb of Sarajevo and a Serbian military stronghold during the fighting of the 1990s. On Saturday, Bosnian Serbs held more celebrations of Princip and his fellow conspirators in Visegrad, 70 miles southeast of Sarajevo, where they also re-enacted the assassination.