OF THE many horrors of the Yugoslav wars, the wanton destruction of the Croatian town of Vukovar by Serb artillery, as well as the expulsion or massacre of much of its population in 1991, was one of the worst. Europe was impotent to stop the bloodshed, despite the vainglorious claim by Jacques Poos, Luxembourg’s then foreign minister, that “the hour of Europe has dawned”. In the end, the wars were halted only by American-led military action and diplomacy.

Since then many, but not all, former residents have returned to Vukovar. Most buildings have been rebuilt, though the cratered water tower has been left as a reminder. These days sandbags are used only to hold back the waters of the swollen Danube. And Croatia’s hour has arrived: on July 1st it will become the 28th member of the European Union. The hour may even be approaching for the rest of the western Balkans. Serbia and Kosovo have struck a deal on the status of the Serb minority in the breakaway territory, and Serbia has been given a firm commitment that membership talks will start by next January. Kosovo will open talks on a “stabilisation and association agreement”, a first step. “Wow!” exclaims the European commissioner for enlargement, Stefan Fule. “Who would have thought this would be possible?”

There is no such elation in Vukovar. Membership offers some vindication: Croatia is now seen as part of Europe whereas, on the far bank of the Danube, Serbia remains in the Balkans. But there is much apprehension, even suspicion, about the change. Having won independence from centuries of rule by Bec (Serbo-Croat for Vienna), Budapest and Belgrade, nationalists do not now want to have to answer to Brussels.

More worry about the impact, on a country whose GDP has barely risen since 2009, of losing access to the free market of the Balkans while being opened up to competition from stronger European countries. Are Croatians destined to become bartenders and chambermaids for German tourists on the Dalmatian coast? In Yugoslav times Vukovar was an economic centre between Zagreb and Belgrade. Now it is on the edge of independent Croatia. Many factories—making tyres, shoes and textiles—have never recovered from the war. For the upwardly mobile of Zagreb, free movement within the EU will make it easier to live and work in London or Berlin. For the people of Vukovar, the EU’s new frontier makes it harder to buy cheap food in Serbia and Bosnia. For the moment, Vukovar must trade on its tragedy. River cruisers call in to offer foreign pensioners a bit of war tourism.

The European project was built on the idea of post-war reconciliation between France and Germany. But the concept of reconciliation between Croatia and Serbia still feels alien; non-violence among neighbours is as good as it gets. A mixed city of some 20 ethnicities, Vukovar is a place where relatives of victims have returned and relatives of perpetrators never left. Conversations with Croats who lived through the siege are interrupted by long silences, sometimes tears. Talk to Serbs about the war, and they become vague about who did what. A cemetery outside town has rows of graves of victims. Some are marked, others unmarked and some still undug—ready for the missing (presumed murdered) whose bodies may yet be found. In April Serbia helped find fresh mass graves nearby.

The politics of identity is becoming nastier. A census in 2011 found that Serbs made up just over a third of the population of Vukovar, the legal threshold to demand that Cyrillic script should be included in street signs and official correspondence. For hardliners, this is an affront to the victims’ memory. To others, it threatens the livelihood of young Croats who no longer learn Cyrillic at school and might be excluded from municipal jobs. It does not help when Serbia’s president, Tomislav Nikolic, is quoted claiming that “Vukovar was a Serbian town”—though he denies it.

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The best-known symbol of the siege is the hospital, where patients and staff were crammed for months in the basement, with little water or medicine, to escape the bombardment. These days the restored building is gleaming white. When Vukovar fell in November 1991, 200 patients were taken from the hospital and shot by Serb forces. Vesna Bosanac, the hospital director, who had been captured, is back in charge. She sums up the contradictory emotions: being part of Europe is not a privilege, but a right denied for too long; the conditions placed on Croatia were frustrating compared with the lenient treatment given to Romania and Bulgaria; but, in the end, Croatia is better for it. Corruption thrived after decades of communism, a war economy and a privatisation process that favoured political friends of the government. Now Croatia will have to learn to live by “European rules”. Serbia should do so, too, even if it will take many decades. Has she visited Serbia, where she was born, since the war? No, she replies. She will cross the border only “when Serbia joins the EU”.

Bulwark of democracy

From now on EU enlargement will become harder. But it would be a mistake to let Croatia become the permanent new frontier of Europe, the Antemurale Christianitatis (“bulwark of Christianity”) of olden days. Rather it should be the gateway for the rest of the Balkans. For all its troubles, the EU is still a family that others want to join. And the lure of membership remains a powerful incentive for economic and political reform among its neighbours, including in countries in the former Soviet Union.

Membership cannot mend everything. The process has not overcome the bitterness of Vukovar’s people. Nor is it certain to fix the Balkans’s many troubles. Yet it offers the best hope of promoting the rule of law and stability. Having failed the people of Yugoslavia in 1991, Europe must not shut the door now.

Economist.com/blogs/charlemagne