The arrest of Radovan Karadzic, the wartime Bosnian Serb leader, is a triumph for the rule of law, the pursuit of justice and the development of real peace in the war-torn states of the former Yugoslavia.

It has taken too long for the man accused of organising Europe’s worst atrocities since the second world war to be caught and put on his way to the international war crimes tribunal. But now that he has been captured, almost 13 years after he was first charged with war crimes, genocide and crimes against humanity, Europe should breathe a collective sigh of relief.

While he was at large, he haunted the families of the many victims of the genocidal civil war he provoked in Bosnia. Now that he is in jail, they may find it easier to deal with the past and think of the future.

His capture is welcome vindication of the principle of pursuing alleged war criminals. Serbs have accused the tribunal of targeting Serb suspects while putting little energy into chasing Croats, Bosnian Muslims and Kosovo Albanians. But a measure of justice has been done in The Hague, with 56 convictions among the 161 suspects who have been indicted. The main challenge now is to arrest General Ratko Mladic, the Bosnian Serb military commander, who is accused, alongside Mr Karadzic, of responsibility for the murderous Sarajevo siege and the Srebrenica massacre. Both deny all charges.

Mr Karadzic’s arrest is a big success for Boris Tadic, Serbia’s European Union-oriented president, and the liberal government that replaced a nationalist-led team in elections this year. Belgrade’s poor record of co-operation over war crimes was blocking its integration with the European Union. The Union must now activate Serbia’s pre-accession association agreement and consider granting candidate status. All this will help Serbia cope with the loss of Kosovo. But, in the longer run, General Mladic must be captured before Serbia even comes close to full membership.

It is years since Mr Karadzic wielded power in Bosnia. But his legacy persists in the dysfunctional state and the poisonous relations between Serbs and their Muslim and Croat compatriots. His capture may improve the political atmosphere, with even some Serb leaders welcoming the arrest. Brussels must capitalise on this sentiment by delivering rapidly on Bosnia’s recently signed pre-accession pact.

More generally, EU leaders must use Mr Karadzic’s capture to encourage the faster integration of the former Yugoslavia. It is not charity to be generous to troubled neighbours. It is common sense.