Those two men, the most important figures in the Bosnian Serbs' bloody war of expansion against their Muslim and Croat neighbours, were still holed up in eastern Bosnia - Karadzic in his Pale fastness just outside Sarajevo, and Mladic in a bunker near the little eastern Bosnian town of Han Pijesak.
Although British army spokesmen yesterday refused to confirm that they have any immediate intention of capturing the kingpins in the organised carnage of 1992, there is no doubt the United Nations and Nato have now dramatically changed their strategy - from waiting for suspects to fall into their net to actively seeking out.
It is possible that an attempt to capture Karadzic and Mladic could follow at any moment.
British special forces who took part in yesterday's raid in Prijedor will have been heartened by the lack of any popular reaction among Bosnian Serbs to the arrest of two of their most significant former leaders, and the death of one of them.
The arrest of Simo Drljaca, the former police chief of Prijedor, who ran the infamous detention centre of Keraterm and Omarska between April and December 1992 and a key figure in the Bosnian Serb power structure, marks a milestone in the international community's attitude towards the arrest of war crime suspects.
Never before have either UN or Nato peace-keepers dared to go out and snatch a man inferior only to Karadzic and Mladic in importance in the Serb hierarchy, and thus risk an armed showdown with his bodyguards.
The bloodshed that resulted from the attempt to grab Drljaca, which took place at about 9.30am in Prijedor, was only a hint of the carnage that might ensue from any attempt to take either Karadzic or Mladic.
Drljaca was clearly surprised, and when he opened fire on the British troops seeking him, wounded only one of them before he was gunned down in what an Army spokesman in Banja Luka said was self-defence.
Karadzic is reported never to be without an escort of at least 50 well- armed bodyguards, most of whom it can be assumed would go down fighting rather than join their master in the dock in The Hague.
Madeleine Albright, the US Secretary of State, launched the new, much tougher, policy towards arresting war crime suspects last month on a tour of former Yugoslavia.
When she met Slobodan Milosevic, of Serbia, Franjo Tudjman, of Croatia and Biljana Plavsic, the leader of the Bosnian Serb state set up under the 1995 Dayton accord, she spelt out that Washington was losing patience over the non-delivery of indicted suspects to the tribunal in The Hague.
She was also reported to have struck an accord with Mrs Plavsic, in whose fiefdom the largest number of suspects are lurking. Certainly, as soon as Ms Albright left Mrs Plavsic's Banja Luka headquarters, Radovan Karadzic escalated his simmering dispute with Mrs Plavsic virtually into open warfare.
The new tougher approach bore fruit only days later, two weeks ago, when the UN forces in eastern Slavonia, in Croatia, suddenly arrested Slavko Dokmanovic in connection with Serb atrocities in the city of Vukovar at the end of 1991.
Now Nato-led S-For troops have shown that they share the UN's stiffened resolve to go in and apprehend suspects, even in the Bosnian Serb heartland of Prijedor. If Prijedor is not off limits, neither is Pale nor Han Pijesak.
The question, however, is whether this new active policy of seeking out war criminals is shared equally by the Western powers involved in S-For. New Labour's determination to put ethics at the heart of foreign policy has clearly played a part in yesterday's events in Prijedor.
But the British "zone" in Bosnia is limited to the north-west. Karadzic and Mladic are in the east of Bosnia, where the French and Italians are supreme; it is not certain that the French - traditionally the most sympathetic to the Serbs of the Western powers - want to go after two leaders far better armed and less likely to be surprised than the former boss of Omarska and Keraterm.