The nervous wisecracks about Kung Fu movies and body odour of the 13 young men are suddenly broken by the crackle of Kalashnikov fire from insurgents who have declared open war on them in this Sunni Muslim bastion.

The marines turn and rip machinegun fire across an empty street toward the gunmen hiding in rows of brown concrete houses.

The US troops, who are holed up in a number of factories edging the residential sector of the town, some 50 kilometres (30 miles) west of Baghdad, are both eager to fight and terrified knowing they may soon have to take the city house by house.

But they are also wondering what they're doing here and if it will make any difference in the long run.

Six days ago, US commanders launched a campaign here with 2,000 marines to root out insurgents who ambushed four US civilian security contractors whose mutilated bodies were shown on prime-time US television.

Paul Bremer, the US overseer in Iraq, earlier announced a unilateral 24-hour halt in hostilities to enable talks to be held on allowing aid to be moved in to beleaguered residents.

But hundreds of Iraqis have been still been reported killed in the most intense operation since US forces captured Baghdad exactly a year ago and toppled Saddam Hussein's regime.

Hundreds of Iraqis have also fled their homes but were being blocked on the local highway by US forces.

"This is a sad anniversary," First Lieutenant Luke Pernotto said as he herded his men through winding alleys, filled with sewage, past bolted metal gates and the threat of snipers who could be perched anywhere in the ghostly city of minarets, two-floor homes and industrial buildings.

Now sitting in the factory, he reflected on a fellow marine who was shot dead as their convoy raced into Baghdad last year. Others are grieving again.

Lance Corporal Michael Goerlinger wears the boot band of a friend shot dead by a sniper here earlier this week.

Another wears the dead soldier's rank insignia, a metal chevron of a lance corporal. A third wears his green helmet strap.

One minute, Goerlinger, grease streaking his face, thinks of his friend, the next minute he is shooting furiously.

"It's all hazy," he says in a drone. "Nothing makes us angry anymore. It'll hit us all later when this is done."

The marines, many of whom have slept just three hours a night for several days, are now preparing to advance on a residential area for possible house-to-house fighting.

Sergeant Major Ken Jones, a blunt man with more than 20 years in the marines, wonders what will come of the city now known around the world as a symbol of anti-US resistance when the fighting is finished.

"We're trying to figure out at the moment who to hand the city over to. There really isn't anyone to do that. We have Iraqi security forces playing with the bad guys," he says.

There is fear and worry that in the end nothing will be better despite the spilled blood.

"We have to take the city, but what happens afterward? My worst nightmare is the military pulls out and the same shit happens," said Gunnery Sergeant Wallace Mains.

Hours later, his position by a rusting silo is hit by rockets and mortars. Shrapnel rips through the air and another marine lies wounded.

WAR.WIRE