Six centuries ago the Turkish empire conquered the empire that was Serbia. Some Serbians moved toward Islam, others to Roman Catholicism, but many -- mostly monks and shepherds -- held to their belief in the Orthodox church and to memories of the Serbian empire. For these Serbians, bombing by the U.S.-NATO forces is only the most recent in a string of efforts to deprive them of their heritage. PNS editor Franz Schurmann, a professor emeritus of history and sociology at U.C.-Berkeley, is author of numerous books on world affairs.

Every Serb knows the story of the Battle of Kosovo Polje, the "field of blackbirds." In June 1389 the forces of two empires -- Serbian and Turkish -- clashed in a ferocious battle. The flower of Serbian and Turkish youth perished. In desperation, a Serb prince pretended to defect to the Turkish side. Once in Sultan Murad's tent, he stabbed him to death. Nevertheless, the Serbs lost the battle and their king Lazar was beheaded by the Turks.

Despite immense losses the Turks won. They moved on to ever greater heights as the Serbian empire bit by bit crumbled. Serbs fled to the hills where, for the next four centuries, they herded sheep. Their towns and villages filled with all kinds of strangers and the slim minarets of Islam rose by the thousands.

Many Serbs converted to Islam. In Bosnia especially, great Muslim families thrived. Farther north and west they became Catholic where they enjoyed the protection of the growing Austrian empire. Their descendants, now called Bosnians and Croats, do not have so many ancient grievances.

The Serbs do.

Far up in the mountains, especially in the Kosovo region, beautiful Orthodox Christian monasteries remained. Within less than a century it seemed that all that was left of the proud empire were monks and shepherds -- and the memory of the glorious days of Stefan Dushan.

Some decades before Kosovo Polje, Stefan proclaimed himself Caesar -- Tsar in the Slavonic languages. He acted because what remained of the Eastern Roman Empire in Constantinople had degenerated into a crumbling enclave. Stefan vowed to save Orthodox Christianity not only from the heathen Turks but from the scheming papacy. After Kosovo Polje, the monks kept that memory alive.

But when the forces met at Kosovo Polje, there were Christian fighters allied with the Sultan and Muslim fighters allied with Lazar. The pure struggle between the heavenly and the earthly kingdoms was sullied by politics. What gave the Turks victory on that day was a politics better than that of the Serbs.

The mountain shepherds, organized into clans, kept a vow of vengeance alive and passed it down through the generations -- so that one European observer claims "vengeance for Kosovo Polje has been the main aim of Serbian politics during this century." In the early 1800s, Serbian nobles and their guerrilla fighters finally got their state. Victory in World War I gave them their empire back in the form of the new Yugoslavia. After World War II Tito ruled Yugoslavia as a Tsar, like Stalin in Russia.

Slobodan Milosevic, who took power in the late 1980's, was a shrewd Communist operative. It wasn't hard for him to pick up a new ideology. He revived the monks' religion, Orthodox Christianity, and found no difficulty in grafting a vengeance-seeking nationalism onto it. But this time -- unlike the situation in both world wars -- Serbia has gained no support from the outside, not even, really, from Russia which has been mired in its own messes.

After frightful killings the Serbs lost in Bosnia and saw a new empire moving in. This new empire has no name but it is American and its fighting forces are NATO, coming in from both a Northern and a Southern Command. To a lot of Serbs, this new enemy looks like a hybrid of the Turkish and the Austrian empires.

As NATO missiles and planes unload their bombs on Serbian "military" targets a lot of Serbs must be wondering whether this will turn into another Kosovo Polje.