The lessons of urban warfare reach across thousands of years, and all the way to Saddam Hussein’s Baghdad. Ancient Greece, World War II Stalingrad, Somalia and Chechnya in the 1990s: all have seen armies pull back into cities and wait for an enemy to wade into hostile territory.

As thousands of U.S.-led fighters push toward Baghdad, coalition officials say eventual victory isn’t in question. But history warns that the cost of victory can be painful and lasting.

Unless Iraq surrenders or the government collapses, capturing Baghdad will require sending coalition forces into the heart of the city of 5 million, where Saddam’s most loyal soldiers will be waiting. Backed by heavy armor and following precision bombing strikes, coalition troops will slowly carve the city into manageable sectors.

Vastly superior technology, enormous numbers of potential reinforcements and constant resupply mean the coalition has little chance of failure, most analysts and historians say. But they disagree fiercely on the course of the coming days and weeks.

“The body count is going to be enormous,” said Tim Ripley, a defense specialist at Britain’s Lancaster University.

But Antony Beevor, a historian who has written extensively about the World War II sieges of Berlin and Stalingrad, predicted the exact opposite. “The idea that it’s going to be very bloody is ridiculous,” he said.

Extensive civilian casualties, widespread infrastructure damage, a prolonged siege: all these could turn Iraqis deeply against the Americans. In the worst-case scenario, what was supposed to be a liberation could end up a bitter postwar occupation.

The chances of an extended siege of Baghdad, such as Germany’s years-long assaults on the Russian cities of Stalingrad and Leningrad during World War II, are minimal. Saddam’s regime is not believed to be able to hold out more than a few weeks at most. And the coalition, already facing widespread international criticism for the war, could never afford the civilian casualties of those battles.

American officials, well aware of the dangers of urban combat, repeatedly have made clear they want to avoid civilian casualties and the destruction of nonmilitary targets.

But that must be balanced against protecting the U.S.-led forces. Some estimates have said a street-by-street Baghdad battle could cost the coalition thousands of dead soldiers, a number that may not be acceptable back home.

Saddam’s regime has proven more resilient than some had expected — and willing, as Beevor puts it, to sacrifice civilians “on the altar of public opinion.” The more resilience there is, the more firepower will be needed to end the war.

“This is where things may blow back even more in the faces of the U.S.,” Beevor said of postwar Iraq, where anger about civilian deaths and political turmoil in the aftermath of Saddam’s downfall could leave the country destabilized and divided.

With little experience in urban warfare, American forces have trained intensively in recent months. But the lessons of battles-gone-bad stretch back in history.

More than 2,000 years ago, the king of Epirus, part of what is now Greece, fought the Romans in a series of battles.

After winning one battle but suffering horrific losses, King Pyrrhus uttered a phrase that, still today, has him immortalized in military history lessons as the father of the “Pyrrhic victory.”

“One more such victory,” he said, “and I am lost.”