NORTH OF BANI WALID, Libya (Reuters) - The hilltop desert badlands of Bani Walid could be where Muammar Gaddafi's supporters make their final stand. They could hardly have picked a better place.
With its severe geography exposing any attacker to raking gunfire, the town southeast of Tripoli was one of the last places to fall to Italian colonialist troops last century and has long been known as a refuge for defenders.
Bani Walid was "built for last stands," said Geoff Porter, an independent U.S. expert on North African politics.
"Every country has a 'maquis' -- a back-country redoubt where fighters have hidden and held out over history," he said, using a term for the impenetrable highlands of Corsica which has given its name to countless guerrilla groups and their hideouts.
"Bani Walid is Libya's 'maquis'."
Interim government forces trying to wipe out the last bastions of Gaddafi support have had some success in redoubts in the deep Sahara desert, and even in Gaddafi's staunchly-defended home town of Sirte along the Mediterranean coast.
But here, repeated attempts to storm Bani Walid town have been repulsed, leading to chaotic retreats and recriminations.
The town is strung along the tops of a rang of hills, geography that compels attackers advancing from the north to traverse a gully, exposing them to withering gunfire.
Chaotic organisation, lack of leadership and factional rivalries have wrecked the cohesion of the anti-Gaddafi push on the town, turning their assaults into debacles.
Some Libyans believe Gaddafi's most politically prominent son, Saif al-Islam is inside the town, helping to explain why its defense has been so stubborn. Anti-Gaddafi fighters insist that the lay of the land, not the skill of the town's defenders, is the only factor frustrating their advance.
"The people who are fighting against the revolutionaries right now are the garbage who escaped from Gasar ben Gashir, Zawiyah, Algerat, Tarhouna," anti-Gaddafi commander Dawo al Salhein told Reuters, referring to other captured towns.
"They have all escaped to this valley of Bani Walid, and for us the geography of the place is what's holding us back, not the (enemy) forces."
Any realistic military plan to capture Bani Walid runs the risk of killing civilians who may not yet have fled.
The town is home to Libya's biggest tribe, the Warfalla, and an assault that caused heavy loss of life could provoke their rage agains the interim government. Residents who have fled or joined the side of the interim government have been keen to ensure that the homes of relatives are not touched.
Brigadier Benjamin Barry, a former British army officer and now Land warfare expert at the International Institute for Strategic Studies, said a siege might work, or, if civilians have fled, an assault by a professional military equipped with tanks and heavy armour.
"The consensus amongst military professionals would be that if there is no other way to persuade defenders who know their business to abandon a defended town, there is no alternative to a combined arms assault by well trained infantry supported by tanks, artillery and sappers," he told Reuters.
"The alternatives are to stand off and flatten the place with various forms of high explosive, or to encircle the place and starve the defenders out, which might eventually force them to attempt to break out."
While many civilians have fled, some are still believed to be in the town, normally home to more than 100,000 people. Flattening the town with big guns and NATO bombing is probably politically out of the question.
Shashank Joshi, an Associate Fellow at the Royal United Services Institution, said pinpoint strikes by drones supplied by NATO member countries might have a role, as would special forces used as advisors.
"Drones have high loiter times, excellent sensors, and high accuracy -- they were used to great effect in Misrata and Zawiyah, and they would be perfect for eliminating loyalist artillery inside the city perimeter.
"The problem is the low number of drones available and the fact that Sirte and other locations are still combat zones."
The anti-Gaddafi forces are probably too disorganised to mount a commando raid, he said.
"So, in short, I think a qualified siege would be best placed to slowly force Bani Walid to capitulate -- qualified, because it'd be just as much a strategic disaster to starve the town as it would be to shell it."
After several weeks of trying to capture Bani Walid and Sirte simultaneously, the transitional government appears to have decided to concentrate its best forces on Sirte first, and only later march on Bani Walid.
Porter said that sequence makes sense: "The collapse of Gaddafi's hometown would reverberate amongst the dead-enders and could facilitate the fall of Bani Walid."
Ultimately, though, the greatest factor working against anti-Gaddafi fighters at Bani Walid may be their own disunity. That may continue as long as the National Transitional Council has yet to allocate posts in the interim government.
Fighters from the west of the country, who led the capture of Tripoli, want more say in a transitional government drawn mostly from the city of Benghazi in the east.
"There may be a reluctance among some groups to really throw their weight behind the Sirte and Bani Walid offensives until they know how they are going to be compensated," Porter said.
"The last thing a militia would want is to expend blood and treasure to further the NTC's conquest of Libya, only to find out that none of their colleagues or associates have been given a position in government." (Additional reporting by William Maclean and Joseph Logan)
(Additional reporting by William Maclean and Joseph Logan in Tripol; Editing by Christian Lowe and Peter Graff)