Dayton was supposed to restitch the multi-cultural fabric of a society torn apart by three and a half years of war.
Instead, a seemingly inexorable process is unfolding in which Serbs are relocating themselves in exclusively Serb parts of Bosnia, Muslims in exclusively Muslim parts and Croats are in exclusively Croat parts.
There seems little that the Nato-led peace implementation force can do about this. In an effort to persuade thousands of Serbs in the Sarajevo suburb of Vogosca not to flee their homes because it was coming under the control of the Muslim-led government, Nato troops distributed leaflets proclaiming: "Don't believe the rumours! You can stay in your homes!"
The appeal symbolised the West's noble, idealistic intentions in Bosnia, the hope that pluralism and trust might replace bigotry and fear.
However, as an attempt to dispel the poisonous atmosphere of paranoia, propaganda and intimidation that has pervaded the five Serb-held districts of Sarajevo since last December, the Nato leaflet campaign stood no chance.
The Bosnian Serb authorities have much to answer for. They vastly exaggerated the prospect of Muslim-inspired retaliation against Bosnian Serb civilians in Vogosca. By closing shops, schools and banks, by extinguishing every opportunity for their fellow Serbs to go about their daily business in peace, and by stoking fears of persecution, they left the people of Vogosca with little choice but to abandon their homes and seek refuge in Serb- controlled zones of Bosnia.
Staff at the Sarajevo office of the United Nations High Commissioner for Refugees are in no doubt about the culpability of the Serb authorities. "We think that the departure of Serbs from Serb suburbs in Sarajevo is political manipulation," said a UNHCR spokeswoman, Christaine Berthiaume.
For sure, the Muslim authorities in Sarajevo could have shown more sensitivity. When they submitted to the UN a list of 85 policemen due to constitute the new police force in Vogosca, 84 candidates were Muslims and one was a Croat.
Eventually, it was agreed that the first police patrol in the suburb should contain 16 Muslims, 14 Serbs and two Croats, a mixture roughly reflecting Vogosca's pre-war national composition. However, in terms of confirming the Serbs' worst suspicions about Muslim intentions, the damage had been done.
The fundamental point remains that the Bosnian Serbs leadership is intent on exploiting the Dayton agreement to achieve in peace what it only partly achieved in war. This is the permanent separation of Serbs from Muslims and Croats in Bosnia, the establishment of a purely Serb political entity, and the eventual unification of that entity with Serbia proper.
The mass departure of Serbs from Vogosca is a dagger plunged into the heart of the Dayton agreement, a blow from which Bosnia's unity and territorial integrity may never recover. As Carl Bildt, the European Union's representative, observed yesterday: "If there is ethnic separatism in Sarajevo, I fear it could have repercussions for the whole of Bosnia in the future."
During the war, the government-held sector of Sarajevo was held up as a model of multi-national co-existence, an area where Muslims, Croats and Serbs still lived and worked together despite the triumph elsewhere in Bosnia of the principle of national exclusivity. The Dayton agreement attempted to extend this model to the whole of Sarajevo, but provided no real mechanism for overcoming the wrecking tactics of the Bosnian Serb authorities.
The collapse of the Dayton ideals in Sarajevo can only complicate efforts to reunite Mostar, the southern city where Bosnian Croats and Muslims are divided into separate sectors. The Croats are primarily responsible for the division, having pursued a wartime policy of turning Mostar into the capital of a distinct Bosnian Croat state.
Last Tuesday Croat and Muslim civilians were supposed to be allowed full freedom of movement across the city, but Bosnian Croat policemen did their best to sabotage the agreement, throwing up checkpoints and demanding identity documents. Western governments can exert some influence over events in Mostar by applying pressure on President Franjo Tudjman of Croatia, who has the power to discipline his Bosnian Croat minions but seems unwilling to use it.
There is little doubt that Bosnian Croat recalcitrance, and Croatia's scepticism about Bosnia's prospects for survival as a united state, will be reinforced by the defeat of the multi-national principle in Sarajevo.
At this early stage of the peace, it may seem alarmist to predict Bosnia's eventual partition, but the Serb flight from Vogosca is a very bad omen.