Libya's revolution was facing collapse as Muammar Gaddafi's forces broke through the last major line of resistance before Benghazi, the heart of the uprising and the seat of the rebel administration.
Pro-Gaddafi troops pushed back the rebels in an air and land assault on the town of Ajdabiya, as the regime moved to crush the revolution once and for all before foreign powers could agree measures in support of the uprising, including a no-fly zone.
The rebels had pledged a vigorous defence of Ajdabiya but swiftly lost control of large parts of the town, including the strategically important coastal road, although pockets of fighting continued. The regime's advance leaves the road open to Benghazi, 90 miles away, where there was growing alarm as word of the assault spread.
"The battle is lost. Gaddafi is throwing everything against us," a rebel officer who gave his name as General Suleiman told Reuters.
The revolutionary leadership promised a fight to the death but some Benghazi residents were fleeing to the Egyptian border last night amid considerable bitterness at the failure of western countries to back up vocal support for the rebels with practical help, including a no-fly zone and military equipment to fight Gaddafi's better armed forces, some of them trained by the British army.
"They have betrayed us," Ahmed Malen, one of the revolutionary volunteers pasting anti-Gaddafi posters on walls in Benghazi. "If they kill us all, the west will have blood on its hands. They do not believe in freedom. They are cowards."
Witnesses in Ajdabiya last night said that they could see tanks on the
streets which they believed belonged to Gadaffi's forces. They
reported continued small arms fire but said that most of the fighting
appeared to have died down.
The regime's strategy to defeat the rebellion before international support for the uprising could be galvanised seemed to be paying off as the US finally joined British and French support for a draft UN resolution imposing a no-fly zone over Libya. A vote on a draft motion is expected later this week or early next week, which is likely to be too late for the rebels.
State television declared: "The town of Ajdabiya has been cleansed of mercenaries and terrorists linked to the al-Qaida organisation."
The assault in Ajdabiya is the latest in a series of reverses that has seen the fortunes of the revolution rapidly set back after the initial successes that had many Libyans believing that Gaddafi's regime was on the brink of collapse a fortnight ago.
Many in Benghazi are now fearful of retribution by the regime's agents and saying they have no choice but to fight for their survival. But the rebel army does not appear to have made any significant preparations for the city's defence.
The attack on Ajdabiya took on a familiar pattern with Tripoli's forces first bombing and then shelling the town. Gaddafi's army then came at the town from two sides. A call went out through mosques in the town and rebel fighters moved to the front but they said they were outgunned and began pulling back.
Some of Ajdabiya's 135,000 residents had already left. Others immediately piled in to cars and fled along with some of the rebel forces.
The revolutionaries initially made a stand at the western entrance to the town but that swiftly collapsed and the street-by-street fighting promised by their military leader, Abdel Fattah Younis, two days ago failed to materialise.
Younis, who was Gaddafi's interior minister and who now has a $4m (£2.48m) bounty on his head, had said that the supply lines to Tripoli's forces were overstretched and that its soldiers lacked the motivation for street fighting.
But that proved to be an overly optimistic interpretation of the situation and Younis's own, largely inexperienced fighters, many of whom are young men with no military experience, were overcome.
Gaddafi's seizure of the coastal road at Ajdabiya opens the way not only to Benghazi but to the eastern oil town of Tobruk and for the regime to take back control of Libya's border with Egypt.
The main coastal road divides at Ajdabiya, offering Gaddafi's forces the opportunity to bypass Benghazi to seize towns to the east and then to lay siege to the rebels' de facto capital from both sides.