Sitting in the bed of a pickup rumbling full throttle toward the frontlines of the Libyan opposition’s struggle against Muammar Qaddafi, Salim Fatah bin Kayali grins into the wind and insists “there’s no stopping us now.”

The bookish and deeply pious young man is sharing a 25-year-old AK-47 with a friend from his hometown of Derna and admits he’s never fired the weapon before.

He participated with rocks and Molotov cocktails in the fight to drive Qaddafi’s forces from Derna, in eastern Libya, two weeks ago, and says he’s eager to do “whatever I can for our revolution. Qaddafi is a terrorist, and he’s divided our people and stole our money for too long.” His father – who was jailed for seven years after a business deal he made with a relative of Qaddafi’s soured -- produced the old rifle when his son insisted he was heading west.

But today, Mr. Kayali was destined for disappointment along with his truckload of would-be rebel fighters, as the front line kept shifting ever westward before they could catch up.

Kayali is part of a disorganized surge west of pickups, private sedans, and ambulances carrying doctors and medical supplies. Under way for days, it is also bringing food provided by businessmen in Ajdabiya and Benghazi, ammunition salvaged from military bases, and about a thousand men determined to take the fight to Qaddafi.

A strange, almost formless war

It’s part of a strange, almost formless war that would shock the Allied and Axis generals that contested the northern Libyan Desert for years during fierce fighting in World War II.

The irregulars of the emerging rebel army, with limited coordination, weak communications, and disorganized supply lines, appear to be easy pickings for any organized military force that might oppose them. But so far, they’ve gone from strength to strength against an enemy that appears even weaker.

Starting from the oil town of Brega, which saw fierce fighting as an incursion by Qaddafi loyalists was beaten back on Thursday, they raced 40 miles on, past the airport and oil refinery at Ras Lanuf, where bullet casings on the ground and burned-out cars are a reminder of the battle for control of this key city that the rebels won yesterday.

Ras Lanuf, which saw pitched battles yesterday that claimed 17 lives, is oddly quiet, with just a few militiamen at a checkpoint. The participants in the previous day’s battle have already pushed on along the coast. Thirty miles on comes the town of Bin Jawad, which the rebels seized this morning without much of a fight.

Here, the rebels are massing.

A few hundred men in mismatched fatigues, hooded robes, and T-shirts mill along the main road, burning the green flag that Qaddafi introduced to Libya, participating in a firing squad for a poster of Qaddafi propped up in the desert, and firing anti-aircraft guns into the air, apparently for fun.

A group of local youths go about the business of setting fire to the local reading room for Qaddafi’s “green book,” the rambling pamphlet he penned and that underpins his one-man rule in a town that just a few hours before was too frightened to side with the rebels or to help Qaddafi.

But then a rumor flashes through the group that a force of 600 “mercenaries” in Qaddafi’s employ are waiting for them down the road. The fighters with heavy-machine guns mounted in their pickups or lucky enough to have rocket-propelled grenade launchers race off first, followed by the rest of the odd, martial cavalcade.

Within 15 minutes, the Bin Jawad checkpoint is quiet again, a few gunmen mixed with excited local residents. By nightfall, the group had made it as far as Nufala, which they claimed without firing a shot in anger. No mercenaries or other pro-Qaddafi forces were found.

Gaining 150 miles

In three days, the at least nominally rebel-controlled zone on the eastern coast has extended about 150 miles and is now knocking on the doorstep of Sirte, Qaddafi’s hometown and his major stronghold after the capital, Tripoli.

Back in Benghazi, civilians working with the transitional government claim that some branches of Qaddafi’s own tribe are turning against him, and that the rush west is having a powerful effect on fence-sitters.

“It may not seem sound militarily, but I think this is working to our advantage,” says Jalal al-Gala, a businessman who acts as an informal spokesman for the transitional government. “It sends a message we’re coming, and is encouraging people to abandon Qaddafi."

The young men, flush with easy gains, insist they’re heading to Sirte tomorrow. It’s hard to imagine the town falling without a tough struggle, filled as it is with relatives and tribesmen of Qaddafi’s who, unlike the Libyan public at large, have profited from his rule.

“Those are the people who fight for him – the ones who have gotten money,” says Abdel Hamid, a contractor from Adjabiya who’s using his truck to ferry fighters west. “The only thing the rest of us have gotten from our oil is the bad smell and pollution in the sea.”

Qaddafi forces active in rebel territory

And Qaddafi’s forces are still active in eastern Libya. In Ras Lanuf, where a crude oil pipeline ends at a refinery, a pro-Qaddafi helicopter bombed a small ammunition dump at a military base outside town.

In the early afternoon here, the rebels said the anti-aircraft guns of the rebellion claimed their first success, taking down a MIG fighter jet and killing its two pilots. The wreckage of the plane and the dead airmen lend support to that claim.

Now, two crucial oil depots have fallen to rebels in as many days. Residents of Zawiya, a major oil town just west of Tripoli that has withstood repeated attacks by Qaddafi’s forces in recent days, say government forces shelled the town with tank-fire this morning, and claimed dozens were killed.

IN PICTURES: Qaddafi: A look back