This is the part of Libya's civil war where there's movement, and you can move with it.
The rebels in Benghazi to the east have been stalled for months, still some 700 miles from Tripoli across the Gulf of Sirte. They're pinned down too in Misrata, also east along the coast, in no shape to move toward the capitol.
But in the Nafusah Mountains southwest of Tripoli, rebel forces have made significant progress in the past several weeks, aiming now for the Gadhafi army garrison town of Garyan, less than 60 miles from the heart of the Gadhafi regime.
There’s brave talk: "Yes, we are ready to attack soon at Garyan," Col. Juma Ibrahim told us in an interview in the town of Zintan.
Imbrahim, a 30-year veteran of Gadhafi's Air Force who's now fighting for the rebels, told us he's in daily contact with armed rebel forces in Tripoli, waiting for the signal that the time is right for a coordinated move to take Gadhafi out.
"Many groups" of rebels, he repeated, offering a genial smile.
I ask him how he thinks the war will end. "Gadhafi will die," he says, "or he will be in prison."
He says Libya's leader for the past 42 years will not be permitted to leave power and continue to live in his home country, or to live in exile elsewhere at the invitation of another nation.
But when we drove out to the front lines of the mountain campaign we saw that that conclusion is a time away.
Plumes of smoke
Supposedly the rebels had taken incremental steps toward Garyan, seizing control in the town of Kikla and winning over most of Qawalish, barely 10 miles from Garyan.
But when we began our drive we saw hundreds of rebel troops scrambling to get ready for battle, fueling up their pickup trucks and assorted transports and loading them with weapons and ammunition: The word was Gadhafi's forces had taken back Kikla and perhaps even Qawalish, driving the rebels into retreat.
Sure enough, at a checkpoint west of Qawalish, we saw the smoke plumes of artillery and rockets on the horizon, and found ourselves at the edge of a sustained exchange of heavy bombardment.
A rebel soldier driving back through our checkpoint told us Qawalish had indeed fallen.
Reinforcements arrived, along with trucks carrying food and support gear for an extended siege.
The hiss and thwack and boom of heavy artillery coming and going continued, one incoming rocket landing on a ridge a few hundred yards from our position.
A whole platoon of rebel troops raced up the hill to check for any injuries; there were none. The fighting continued.
It's hard to assess the rebels' chances with any precision.
Earlier in the war, when the first advance from Benghazi stalled and was turned back, it was clear from the video shot by news crews that the rebels were poorly equipped with ancient weapons and so disorganized they could hardly be called a credible fighting force.
But in the Nafusah Mountains we saw evidence that over the months an actual army is forming. In every town we passed through … Nalut, Jadu, Zintan … there are enough volunteers, most of them very young, to fill up one class of trainees after another, each class going through six weeks of preparation before heading off to join the fighting.
Slideshow 81 photos
Libya's uprising against Gadhafi
Switching sides
How big an army? Again, hard to say, but several leaders told us there were between 2,000 and 3,000 in the mountain campaign alone.
There's also the question of motivation, and the role motivation plays in a war such as this one.
Typically, any revolutionary force is fueled by an ardor born of frustration and rage against an oppressive regime, and that's surely true in this case.
And there are an untold number of veterans of Gadhafi's military — Col. Ibrahim one example — who've switched sides eagerly at a time when a revolutionary campaign actually seems capable of succeeding.
The rebels are accumulating hundreds of prisoners; many offer to switch sides immediately.
Many others appear to be mercenaries; when we went to a prison in Zintan we videotaped scores of prisoners and spoke with some of them. One man, a Nigerian, said he'd been fighting for Gadhafi because he’d been paid the equivalent of $750 to do so.
"They are fighting only for money," Col. Ibrahim said, "or because they have no choice. They cannot win." He says it resolutely, but it sounds more like a hope than a certainty.
The simple truth is that the rebel forces, as a "war machine," lack many of war’s essentials.
They're badly under-equipped, compared with Gadhafi's army, even though they showed us some of the tons of ammunition and weaponry — everything from 30-caliber machine gun rounds to mortars and Russian-made Grad rockets that have been recovered from the garrisons and weapons armories they've overtaken.
And every rebel leader and spokesman we've questioned agreed that without more help from NATO — if not help on the ground than at least coordinated air strikes to plow the road toward Tripoli — their capacity to advance will hit the wall.
And the mountain campaign will be another Benghazi, another Misrata, and Gadhafi will announce again on Libyan state television that all his people love him and the "terrorists" have been turned back.
Because in the end, it doesn't matter if the hand that fires the bullet is that of a soldier motivated by fear or money, or of a revolutionary propelled by dreams of freedom: the bullet still kills. And the army with the most bullets usually wins.
Town retaken
By nightfall on the day of our first visit to the front, the word filtered back that the rebels had retaken Qawalish.
We had no way of confirming whether that was true, and we planned our next foray forward on the assumption that the battle, even for that one town, was hardly over: We'd seen the smoke and heard the explosions of Gadhafi's daylong bombardment.
Tripoli? I'd been there, staying in the one hotel allowed for foreign journalists, who all worked under the strict control of the regime’s minders.
We'd seen what the minders allowed us to see: Schools and residential neighborhoods struck by NATO's air sorties, the compound where Gadhafi's son Saif was killed in June, the shouting demonstrations of green flag-waving support for "the leader" that were clearly staged for our cameras.
By whatever means, after 42 years Tripoli still belongs to Moammar Gadhafi. He will not give it up — and the rebels will not take it from him — easily, or soon.
Additional reporting by NBC News producer Charlene Gubash