DIWANIYAH, Iraq — The American convoy loaded with fuel and ammunition resumed its northward march on Thursday, marshaling its 300 trucks in a line that stretched for miles.
Then the Iraqis began firing, and the convoy turned around, leaving its store of shells and diesel fuel in the same place it was three days ago.
The firefight that unfolded on Thursday in front of the American caravan illustrated the difficulty the military is having here in resupplying its troops at the front line.
The rapid advance of American forces through Iraq has left the spearhead of the Army 300 miles away from its main base. As a result, the supply lines are stretched thin and are vulnerable to the kind of attacks that have left this convoy standing still since Tuesday.
"The firing was very close," said Col. John Pomfret, who is leading the convoy. "We're going to have to wait."
Pomfret will try again to take his convoy north on Friday in hopes of supplying the 22,000 American Marines gathered about 10 miles to the north. He says that despite the recent attacks, he will be able to get his supplies through without any disruption.
But here in the parched plains of central Iraq, it is much less clear that the American military can stop the harassing Iraqi attacks that have delayed the caravans .
The Marines running the convoys say they can fight their way through just about anything the Iraqis can throw at them. But with their supply lines reaching all the way back to Kuwait, the experience of this convoy suggests that the Marines may be doing a lot more fighting than they bargained for.
The Marine convoy is a gigantic thing, involving trucks and tankers and jeeps and tanks, carrying thousands of gallons of diesel fuel, millions of rounds of ammunition, and crate upon crate of ready-made meals. So large is this caravan that it takes several hours for all of its vehicles to pass through a single point. Among its cargo is 160,000 gallons of fuel and 180 tons of ammunition.
Yet it is a measure of the voraciousness of the modern army that this convoy, 300 vehicles long, carries only enough supplies to last the 1st Marine Division a few days. Its guns can shoot thousands of shells in a single day; it takes as much as five gallons of diesel fuel just to start the engine of an M1 tank. The key to the Marines logistical success is its ability to keep the train going, to keep more caravans, just as big, rolling north.
So far, the path of the convoys as they travel across central Iraq has been anything but smooth. They have come under constant fire from Iraqi soldiers, who often wait for the tanks and heavy armored vehicles to pass by before opening fire. Each attack, however small, almost always requires the convoy to stop. In each case here, the Iraqi attacks have been carried out by small groups of soldiers, who capitalize on quick surprise assaults.
Since Thursday afternoon, the fighting has been continuous. Cobra gunships raced back and forth to the front lines, their racks full of rockets on the way out, and empty on the way in. Twice on Thursday evening, American officers sounded warnings for poison gas. All through the night, the ground shook from the tell-tale explosions of B-52 strikes.
All the while, for three days, the convoy was still. The needs of the Marines battling at the front are not dire yet, officers here say. But the constant fire from the Iraqis suggests that the effort to supply American fighters at the front could be a battle itself.
"The logistical people do not want to be the cause of a pause in operations," Lt. Col. Bob Weinkel said.
The Marine convoys have armed themselves heavily to repel the Iraqi attacks. Each caravan is shadowed by several tanks and other armored vehicles, and they have responded ferociously to the recent ambushes. The Marine commanders say they need to respond quickly and decisively to such attacks, in large part because they are so vulnerable.
The Marine convoy stuck near Diwaniyah, for instance, has more than a dozen 60-foot-long fuel tankers. Each one carries 5,000 gallons of diesel fuel.
"I think about it a lot, getting hit," said Gervonne Bell, a diesel truck driver. "I'm a sitting duck." The Marines themselves, even the driver of the smallest water truck, is ready to grab his rifle and fight. It is that, more than anything, the Marines say, that makes them confidant they will be able to keep the caravans rolling north.
"We're not just truck drivers," Weinkel said. "We're truck drivers with guns."