Rebel volunteers train in Kabaw, a Berber town in the Nafusa Mountain region… (Zohra Bensemra / Reuters )
The revolt against Moammar Kadafi was born in the eastern city of Benghazi, long a caldron of discontent with the autocratic ruler.
The uprising gained traction during bloody spring battles in coastal Misurata, Libya's third-largest city, where residents barricaded streets with shipping containers in ferocious urban warfare.
But it is a rebel thrust from the west that may prove decisive in bringing an end to Kadafi's more than four-decade reign.
Photos: Conflict in Libya
The push by guerrilla fighters from Libya's isolated Berber highlands, the rugged Nafusa Mountains near the Tunisian border, was one front too many for Kadafi's depleted and sometimes demoralized forces.
Before the mountain fighters made major gains, Kadafi's troops were already facing grave threats in the east, as well as intensive NATO bombardment that targeted the capital, other key locations and equipment.
NATO bombings made it almost impossible for the government to move large concentrations of troops. Airstrikes by the alliance on Kadafi's armored units in March prevented government forces from retaking Benghazi.
The regime successfully managed to thwart rebel advances into the cites of Port Brega and Zlitan, east of Tripoli, but its ranks were stretched thin, despite reported additions of young conscripts.
That was partly the result of Kadafi's own choices. His army never reached the size of those of Middle Eastern autocrats such as Iraq's Saddam Hussein or the Assad dynasty in Syria. Rebels often said that Kadafi, who led a coup as a junior officer, didn't trust military commanders.
It now seems possible that Kadafi's government, its forces overtaxed, lacking coordination and without any centralized command and control, underestimated the threat from a western rebel force that for weeks has been no more than 50 miles from the capital.
The uprising in the Nafusa Mountains was so little noticed early on that the fighting often barely merited mention as the world focused on dramatic events in and around Benghazi and Misurata.
In the end, however, the western rebels' tenacity and proximity to Tripoli seemed crucial in breaking down what the government had long boasted was a virtually impregnable wall of security around the capital.
As insurgent offensives stalled near Benghazi and Misurata, fighters made up of Arabs and ethnic Berbers, or Amazigh, tenaciously gained ground in the west. There is no indication the western fighters possessed superior firepower or were better trained than their undisciplined comrades in the east. But geography was certainly an ally.
In the east, rebels struggled to move forward in flat desert terrain that proved advantageous for Kadafi's artillery and rocket launchers, often well concealed from allied aircraft. In contrast, the western fighters engaged in a guerrilla war on turf that was intimately familiar to them. Supplies arrived via a captured post on the Tunisian border.
By June, the mountain fighters had largely gained control of the highlands and were filtering into the plains that led to the coast and the capital, the ultimate prize. Tribal links to lowland populations probably aided their advance. Government officials in Tripoli betrayed no sense of alarm.
The western insurgent ranks bulged with new volunteers from places such as Zawiya, a city just west of Tripoli that sits astride the crucial supply route between Tripoli and the Tunisian border. Kadafi's troops had brutally crushed a rebellion there in March.
In June, when renewed fighting erupted near Zawiya, the government dismissed it as the work of a handful of mountain infiltrators who would find no allies in the coastal areas.
It appears the opposite happened. Volunteers from Zawiya and other towns and villages joined the advancing mountain fighters. And the recent capture of Zawiya, which severed Kadafi's supply line, signaled that his days were numbered.
Throughout the conflict, Kadafi's government seems to have rejected the notion that a motley group of mountain dwellers could move on the leader's inner sanctum.
"We're not worried about these so-called rebels," Musa Ibrahim, the government's chief spokesman, said in June after clashes with western rebels erupted anew near Zawiya. "What is a problem for us is NATO."
Still, the North Atlantic Treaty Organization strikes near Benghazi and Misurata ultimately did not trigger what seems to be the final assault on the capital. That task would fall to the fighters from Libya's rugged west.
Photos: Conflict in Libya