Like other refugees before them, those fleeing Drvar were mainly women, elderly men and children, for few men and teenage boys of fighting age manage these days to escape the press-gangs of the Yugoslav successor states. The Drvar refugees even spoke the same language as all the other unfortunates who, since the outbreak of war in June 1991, had been cast out of their native towns and villages.
But there was one difference. These refugees were Serbs, and the 13,000 people who fled Drvar last week in response to Croat military advances represented the largest single Serb refugee movement of the war. Worse may yet happen. International Red Cross officials said on Friday that if Croatia achieved a decisive victory over Serb rebels in the breakaway Krajina region, as many as 100,000 Serb refugees could flee over the border into Bosnia.
The plight of the Drvar Serbs illustrates how the tide of war has turned this year against the secessionist Serb minorities of Croatia and Bosnia. The Bosnian Serbs' ruthless elimination last month of the Muslim enclaves of Srebrenica and Zepa in eastern Bosnia obscured the extent to which the pan-Serb cause was plunging into crisis.
Nowhere is this more true than in Knin, the fortress capital of the Krajina Serbs in southern Croatia. Once a seemingly impregnable stronghold of mystical Serb nationalism, Knin has finally fallen after taking a terrible battering from Croat missiles and artillery.
"The destruction is heavy, houses are burning, streets are full of glass and debris, and many civilian facilities are hit, including Knin Castle," reported a correspondent for Beta, an independent Belgrade-based news agency.
Contrary to the hopes of Serb militants since 1991, it is looking increasingly as if there will be no Greater Serbian state stretching from the Adriatic Sea to the Romanian border. What is more, President Slobodan Milosevic of Serbia, the patriarch of modern Serb nationalism, is turning all predictions upside down by resisting the lure of that same Greater Serbian dream he conjured into existence in the late 1980s and used as a call to arms in 1991.
Four years of warfare in Croatia and Bosnia have produced almost every possible permutation of alliance among the various nationalities and sub- groups, as well as brutality, betrayal and intrigue on a scale matching that of the civil war in the 1940s. Serbs have fought Croats, Serbs have fought Muslims, and Croats have fought Muslims; Serbs and Croats have schemed against Muslims, Muslims and Croats have joined forces against Serbs, and in one area - Bihac - Serbs and a renegade Muslim warlord have conspired against the Muslim majority.
Suddenly, however, the picture is acquiring greater clarity. The wars are condensing into a struggle between, on one hand, Croatia and the Muslims and Croats of Bosnia, and, on the other, the Serbs of Croatia and Bosnia, lightly supported by Serbia. The aim of Croatia and its allies is to restore the territorial integrity of Croatia and Bosnia, destroyed by the twin Serb rebellions of 1991 and 1992. The aim of the Serbs of Croatia and Bosnia is to preserve their rebel states and, one day, with or without the support of Mr Milosevic, to merge them with Serbia and Montenegro into a Serbian super-state.
Croatia's offensive on Krajina, launched on Friday with artillery, warplanes and tens of thousands of troops, capped a turbulent three months of military clashes and diplomatic showdowns. It was at the end of April that a shaky ceasefire, brokered by former US president Jimmy Carter, expired in Bosnia, touching off heavy fighting between Bosnia's Muslim-led government and the Bosnian Serbs.
Croatia's armed forces seized the opportunity to grab back a section of Krajina, known as Western Slavonia, in central Croatia. They accomplished their mission in 48 hours, stunning the Krajina Serbs and sending a message to everyone in former Yugoslavia that Serb military invincibility was a myth.
Significantly, the Bosnian Serbs extended no help to the Krajina Serbs, even though the two leaderships had signed a pact on military co-operation. Equally, no aid was forthcoming from Serbia, although after the enclave's fall, Mr Milosevic sent a senior general, Mile Mrksic, to take command of Krajina's armies. Cracks in Serb unity were becoming increasingly visible.
World attention then returned to Bosnia, where Nato planes bombed Bosnian Serb ammunition dumps in late May, prompting the Bosnian Serbs to seize several hundred UN peace-keepers as hostages. Although all hostages were eventually freed, the episode underlined that Nato's freedom of action was limited in Bosnia as long as the UN forces were relatively lightly armed and deployed in vulnerable places.
Western governments, principally Britain and France, decided to create a 10,000-strong "Rapid Reaction Force" to beef up the UN presence and deter more outrages. But then came perhaps the most defiant Bosnian Serb act of the entire war: the seizure of the "safe areas" of Srebrenica and Zepa, carried out with total contempt for UN Security Council resolutions.
The West felt compelled this time to prepare a stronger response, not least because the capture of Srebrenica was followed by the disappearance of thousands of Muslim prisoners, many of whom were promptly executed. At the same time, the Krajina Serbs joined in the action by launching a combined offensive with the Bosnian Serbs on Bihac, the Muslim enclave and "safe area" in north-western Bosnia.
Nato's riposte last Tuesday, was to threaten the Bosnian and Croatian Serbs with heavy air strikes if either attacked the four remaining Bosnian "safe areas" of Bihac, Gorazde, Sarajevo and Tuzla. It is the closest Nato has come to fighting a real war since its formation in 1949.
Whatever the implications of the Serb assault on Bihac for Nato, its immediate importance lay in the fact that it provided Croatia with a perfect excuse for entering the fighting. An assault on Krajina Serb and Bosnian Serb positions near Bihac could be justified as a way of easing the pressure on the enclave, even if Franjo Tudjman's basic aim was the restoration of Krajina to Zagreb's authority.
Croat forces struck first in western Bosnia just over a week ago, rolling over the Bosnian Serb towns Grahovo and Glamoc. Refugees poured into Drvar and, when Croat forces shelled Drvar, thousands more fled deep into Bosnian Serb erritory.
Then, last Wednesday, UN officials reported that Croatia had massed a battle-ready force of about 100,000 soldiers, poised to thrust into Krajina both from the direction of Zagreb and from the Dinaric mountains towards Knin. Western intelligence sources put the Croatian troop concentration at nearer 70,000. The Krajina Serb forces were estimated to have at most 45,000 soldiers at their disposal.
It became clear on Wednesday and Thursday that Croatia's two most important Western allies, the United States and Germany, had given Croatia an "amber light" to launch an attack on Krajina. The cautionary advice was that the attack should not get out of hand, either by causing too many civilian casualties or by drawing Serbia into the war.
Britain, France, Russia, and the EU mediator, Carl Bildt, were not happy. A Foreign Office statement issued within hours of Croatia's dawn assault on Friday said: "It is clear that the possibility of further negotiations had not been exhausted."
Mr Bildt, a former Swedish prime minister, recalled that the Krajina Serb leader, Milan Martic, had been accused of war crimes by the UN tribunal in The Hague last month for having authorised Serb rocket attacks on Zagreb in May. "It is difficult to see any difference between these actions and the shelling of Knin, for which President Tudjman must now be held responsible," he said.
A key role in influencing Croatia's actions was played by Peter Galbraith, the US ambassador in Zagreb. When Croatia and Bosnia signed a formal military alliance two weeks ago, an official photograph of the ceremony showed not only Mr Tudjman and the Bosnian President, Alija Izetbegovic, but Mr Galbraith at their shoulders.
Mr Galbraith believes strongly in the need for Croat-Muslim solidarity to roll back Serb war gains, but last Thursday he also tried to extract concessions from the Krajina Serb leadership as a way of delaying or limiting Croatia's long-planned military offensive. He appeared to make progress, for the Krajina Serbs told him they were ready to discuss a "modified and improved" version of an international peace proposal that would return Krajina to Croatian authority but give local Serbs autonomy.
The Croatian government, which had already started rounding up draft- age men in raids on Zagreb apartment buildings, dismissed the apparent concessions as a ruse. War was the only thing on Mr Tudjman's mind. Croats woke up on Friday morning to patriotic pop songs and terse military announcements on the state-controlled radio and television.
Initial reports suggest the Croatian offensive has been successful. On Friday the government claimed its forces had captured the key town of Petrinja, south of Zagreb. The Foreign Minister, Mate Granic, said he expected complete victory within a week.
Clearly, though, much depends on Mr Milosevic. He has condemned the Croatian assault and demanded an international response, but has kept silent on whether Serbia plans to intervene. If it does, Serbia's superior military strength - especially its powerful air force - could quickly tell against Croatia.
But a better guide to Mr Milosevic's thinking may lie in an editorial published on Friday in Politika, the main mouthpiece of the authorities in Belgrade. The newspaper accused the Krajina leadership of having "insane ambitions" and said that "peace is unavoidable".
Thus, in inimitably Balkan fashion, a situation has arisen in which the Krajina Serbs, once beloved of Serbia and reviled by the West, are now courted by the West but attacked by Serbia for incompetence. Militant Serbs have condemned Mr Milosevic for selling out their Krajina brethren, but the President, who controls the Serbian security apparatus, police, bureaucracy, parliament and most of the media, appears to hold all the strongest cards at the moment. He was even confident enough recently to let his fiercest nationalist critic, Vojislav Seselj, out of prison.
On one point, however, Mr Milosevic may not yield. The Krajina enclave of Eastern Slavonia, which borders Serbia, is a region that has oil and gas reserves and rich farmland. It is important to Serbia both in economic and security terms, and it seems unlikely that Mr Milosevic would meekly accept the region's return to Croatian rule.
Croatia has so far been careful to restrict its offensive to the area of Krajina adjacent to the Adriatic coast, leaving Eastern Slavonia alone. But yesterday Serb forces fired hundreds of shells on the Eastern Slavonian towns of Osijek and Vinkovci, in what appeared to be a warning that Croatia should not try to bite off more than it can chew.
Eastern Slavonia is an exceptional case. Elsewhere, there are few signs that Mr Milosevic intends to rescue the beleaguered nationalist marionettes of Krajina. Radovan Karadzic, the Bosnian Serb leader, who fervently wants a Greater Serbia, knows something is wrong.
"People are asking themselves a question," he said on Friday night. "Why has the President of the Republic of Serbia, Slobodan Milosevic, given up on the national programme?"