People in Benghazi are becoming increasingly frightened of a second attempt by pro-Gaddafi forces to take the city. For all the propaganda slogans about overthrowing the dictator, it is beginning to occur to many that Nato airpower is not quite the recipe for survival and victory they thought it was a few weeks back.
A good place to judge the balance of forces between Gaddafi and the rebels last week was the western entrance to the deserted town of Ajdabiya, south of Benghazi. The place is marked by a high archway and a wrecked cement sentry box containing scraps of rotting food. On its broken walls are pasted sad pictures of young men who have gone missing, with the phone numbers of their families underneath.
We arrived mid-morning, having been warned that it was a mistake to get there too early: rebel fighters could still be asleep and it was possible to drive straight through the rebel lines, without knowing they were there, and into the frontline of the pro-Gaddafi troops.
This was an exaggeration. Some rebel soldiers in uniform were turning back militiamen and journalists, to the irritation of both. The soldiers cleared the road for giant flat-bed trucks going up to the front with vehicle-mounted Katyusha rocket launchers and a lethal-looking contraption welded to the back of a truck which is, in fact, a rocket firing pod that is normally fitted to the underside of aircraft. In the other direction a couple of dozen flat-bed trucks were coming back from the front to which they had delivered some 20 tanks earlier in the morning.
There was an atmosphere of friendly confusion, like the meeting of a local fox hunt, because we imagined that the frontline was far down the road towards the oil town of Brega. It turned out to be a lot closer than that. Suddenly white civilian ambulances raced past us. A soldier in one of them shouted they had been bombed. He did not say by whom, but we assumed it was another Nato "friendly fire" mistake.
Soon there were plumes of smoke in the distance as four or five shells or rockets landed. Militiamen started streaming back towards Ajdabiya. We stopped at a small hospital there where doctors have become used to examining patients while giving media interviews. They were full of self-righteous and not entirely reasonable rage about Nato bombing the rebels and not Gaddafi's men.
Any event in eastern Libya at the moment can become the occasion for a political rally. In this case the reception of the wounded as they were carried from the ambulances into the hospital was delayed by political speeches and chants of "God is great". Nor did the ordeal of the wounded end there. In hospitals throughout the Middle East, families and friends consider they have a divine right to visit patients. In Ajdabiya hospital, sobbing soldiers crowded into a ward so that stretcher-bearers could hardly get in. Angry doctors manhandled the grieving fighters out of the room for a few minutes before they burst in again.
The Nato attack on the rebel tanks turned out to be much as the first survivors had described it. The rebels had moved up tanks, ageing Libyan army T-54s that had been in storage for 30 years and half a dozen more modern T-72 tanks. They claim they had told Nato but it seems likely, given the general chaos in Benghazi, that they did not. Not surprisingly, the Nato pilots assumed that the tanks must belong to the government.
The incident on the Ajdabiya-Brega road is important because it shows that the rebels are not going to be a serious fighting force for months and possibly not even then. David Cameron and Nicolas Sarkozy have entered a war into which they will inevitably be sucked deeper because the rebel enclave around Benghazi is completely dependent on outside military support.
The Gaddafi forces show ominous signs of adapting faster than their enemies. They fire accurate artillery barrages and attack out of the desert in the same sort of pick-up vehicles as the rebels. What holds them back is that they are at the end of long supply lines and they do not have enough men to hold the ground they take.
The same is true of the anti-Gaddafi fighters. Though there are plenty of people willing to demonstrate in Benghazi there are surprisingly few militiamen at the front. These are often derided by the foreign press for their military ineptitude or lack of experience, but what is most striking is that there are not enough of them.
The roadside from Benghazi is littered with the burned-out remains of tanks and trucks dating from the last time Gaddafi came close to capturing the city. He may not try to do so again and, if he does, it will probably be in vehicles that are the same as those used by the rebels. If the Gaddafi forces do advance, there is nothing much to stop them.
On the road between Ajdabiya and Benghazi, there are no fall-back positions. If the front does cave in, Nato aircraft will have to try to tell a dirty white Gaddafi pick-up with machine gun in the back from a dirty white pro-democracy pick-up similarly armed.
Back in Benghazi away from the chaos of the front, this is not the picture the rebel military commanders want to give. At a press conference, the joint Chief of Staff General Abdul Fattah Younis, former head of Gaddafi's special forces, seeks to give the impression that all is under control. Asked about the Nato bombing of the tanks, he says that "accidents happen in war". He describes the panicked flight of militiamen as a military manoeuvre to throw back a temporary advance by Gaddafi's troops.
General Younis's air of calm is very soothing, and many in Benghazi who have not been near the frontline wish to believe that what he says is true. Libyan reporters clapped and cheered when he said that the rebels had not and would not accept foreign advisers. But this bravado may not last very long. Iman Bugaighis, a Newcastle-trained lecturer in orthodontics at Benghazi University turned rebel spokeswoman, said "we ask them to use attack helicopters" at least in the besieged city of Misrata.
There is an undercurrent of fear in Benghazi, and it would not take much to start a panic. Libyans are beginning to learn the ways of survival well known in countries such as Iraq and Lebanon, where war frequently turns part of the population into refugees. The Kurds, with grim experience of taking flight, have a saying: "If you are going to run, then run early." Wait too long and you cannot get out.