Effects of losing critically important town to Syrian regime are still being felt, as rebels struggle to unite their ranks and make up lost ground. Phil Sands and Suha Maayeh report
Poisonous rivalries between commanders end in defeat for Free Syrian Army
From the jaws of victory however, the FSA snatched defeat - undermined by poisonous rivalries between commanders, failures of communication and weapon shortages.
Regime forces recaptured the town in May, seizing the strategic territory near the border with Jordan in Deraa province while the FSA squabbled.
Six months later, the effects are still being felt, with the rebels mired once again in slow-moving warfare and struggling to unite their ranks and make up lost ground.
The debacle at Khirbet Ghazaleh summarises many of the problems afflicting Syria's rebels, even in Deraa province where, unlike other parts of the country, the Gulf Arab and western-backed FSA forms a relatively coherent bloc and Islamist hardliners allied to Al Qaeda play a less prominent role.
Precise details about the FSA's collapse in the town remain disputed and the topic is sensitive enough that many in Deraa's rebel factions are still reluctant to discuss it openly.
But a profound personal dislike between Ahmed Nehmeh, head of the FSA'S Deraa military council, and Bashar Zaubi, leader of the Yarmouk Brigade, a powerful rebel unit ostensibly under the council's command, played a central role in the defeat.
According to the accounts of more than a dozen FSA members, Mr Zaubi's troops had been in the thick of fighting for about 70 days leading up to early May, taking and holding Khirbet Ghazaleh, a town that rebels say must be controlled if they ever hope to make meaningful advances up towards Damascus.
With the battle still raging, Mr Nehmeh arrived and was filmed proclaiming victory - a recording intended to show the FSA's weapons suppliers in Saudi Arabia and Qatar that their backing was producing tangible results.
None of the Yarmouk brigade fighters appeared in the video however - a slight that, FSA members said, infuriated Mr Zaubi, an experienced battlefield commander with little respect for the smartly dressed Mr Nehmeh, who is based in Jordan.
Adding injury to insult, a supply of weapons and ammunition that Yarmouk fighters had been expecting from the military council failed to arrive.
Conflicting reports about the munitions say they either simply did not exist or were handed out by Mr Nehmeh to units commanded by his own appointees, who were not actually fighting on the Khirbet Ghazaleh front where the weapons were sorely needed.
Either way, in response Mr Zaubi pulled his well-organised brigade out of the fight, approximately 800 men, almost half of the FSA strength in the combat zone.
"Bashar Al Zaubi was so angry with Ahmed Nehmeh for announcing the victory and not delivering the weapons that he said: 'OK, if you've already won, my men don't need to be dying here' and he left," said an FSA field commander in Deraa.
Without the Yarmouk brigade, the remaining FSA fighters had little hope of holding on to the town and withdrew under fire from forces loyal to President Bashar Al Assad.
"To be fair to Nehmeh, he said they couldn't get the weapons up to the Yarmouk brigade because of the heavy fighting, and as for the video, it was just a publicity thing that he had to do to try to drum up more support and money in the Gulf," the commander said.
"It all got out of hand quickly. It was a disaster for us and we still haven't recovered from it."
With Khirbet Ghazaleh in rebel hands, regime forces had been unable to resupply hard-pressed units in the province, including in Deraa city, where the revolution began in March 2011. As a result, regime forces fell back, relying on air power and trying to conserve ammunition.
"As soon as the regime retook the town, they brought in shells and rockets and food for their men, they set up an artillery base, and they have been hitting us much harder ever since. A lot of people have died because of that," the field commander said. "It was a huge setback."
Recriminations set in and, in July, Mr Zaubi publicly demanded Mr Nehmeh be stripped of his leadership of the military council - an influential organisation that liaises with international backers of the FSA and, theoretically at least, orchestrates all military operations by rebels in southern Syria.
Mr Zaubi demanded that Mr Nehmeh be put on trial for undermining the revolution and for mismanagement, and appealed to international donors to stop channelling aid through the military council as long as he retained command.
In response, Mr Nehmeh issued his own public rebuke, accusing Mr Zaubi of refusing to respect the FSA's chain of command, of trying to divide rebel forces and of obsessing over trivial issues.
Mr Nehmeh, who still holds his post at the military council, is not popular among Deraa's FSA units but is grudgingly accepted for his contacts with the foreign powers they rely on for support.
Under Mr Zaubi's command, the Yarmouk brigade remains one of the most important and effective rebel units in Deraa province.
The personal rivalry between the two men continues to simmer, FSA members said, although an uneasy detente had emerged in recent months.
Efforts to increase the level of cooperation between headstrong, autonomous-minded rebel commanders appeared to have borne some fruit with last month's capture of Tafas, a town 10 kilometres east of Khirbet Ghazaleh, by a combined force of different FSA units, although the Yarmouk brigade was not involved, according to FSA fighters in the area.
"It has been a long battle to unify our ranks and our achievements in that regard were important in the liberation of Tafas, it showed we have unified," said a FSA commander supportive of Mr Nehmeh.
Other influential FSA fighters in Deraa warned against overestimating the impact of victory in Tafas.
"It's good that we have Tafas but it doesn't make up for what happened at Khirbet Ghazaleh, there was some treasonous splits there," said another field commander.
"Since the regime took Khirbet Ghazaleh it has reinforced its positions there, if will be even more difficult now than before to try to take it back," he said.
* Suha Maayeh reported from Amman