Resurgent government forces yesterday hoisted the Ukrainian flag over pro-Russian rebels' main stronghold after a devastating shelling assault that levelled much of the city but delivered Kiev its biggest success of the campaign.
The self-proclaimed mayor of Slavyansk confirmed insurgents had abandoned the rust-belt city of 120,000. A local resident said barricades once manned by the camouflage-clad gunmen now stood abandoned.
Ukraine's ability to win back Slavyansk, home to one of the country's biggest weapons storage facilities, which fell to the insurgents on April 6, marks a key turning point in three months of low-scale warfare that has threatened the very survival of the ex-Soviet state.
Ukraine's interior minister, Arsen Avakov, said in a Facebook post the withdrawal was led by senior militia commander Igor Strelkov - alleged by Kiev to be a colonel in Russia's GRU military intelligence unit.
Both Strelkov and Moscow deny any GRU link despite Western claims that the Kremlin is covertly funding and arming the uprising to destabilise Kiev's new pro-European leaders and retain control over Russian-speaking eastern regions of Ukraine.
Ukrainian Defence Minister Valeriy Geletey told President Petro Poroshenko that his forces had raised the national flag over city hall "in accordance with your order to liberate Slavyansk".
A source said the rebels were outnumbered by 50 to one. "The Ukrainian forces have greater numbers of troops and military hardware," the source said.
Aleksandr Borodai, a leader of the self-proclaimed Donetsk People's Republic, was quoted as saying: "The punitive forces of Ukraine ... moved into a large-scale offensive. Given the disproportionate numerical superiority of the enemy troops, units of the armed forces of the Donetsk People's Republic were forced to leave their previous positions on the northern sector of the front."
Poroshenko stormed to victory in a May 25 election thanks to his vow to quickly resolve the country's worst crisis since independence in 1991.
Most analysts think the 48-year-old chocolate baron desperately needed an early success in the campaign to secure the trust of Ukrainians frustrated by their underfunded army's inability to stand up to what they see as Russian aggression.
"The departure of the fighters was a surprise. Nobody was aware it was happening," city resident Kolya Cherep said.
"This morning, I saw that there were no fighters in front of the town hall, then I saw that there were none manning the barricades in town," he said.
Strelkov himself had told the pro-Kremlin LifeNews channel on Friday that his units "will be destroyed ... within a week, two weeks at the latest" unless Russia helped secure an immediate truce or moved in its troops.
Slavyansk is the symbolic heart of an uprising sparked by the February ousting of a pro-Kremlin administration in Kiev and fuelled by Russia's subsequent seizure of Crimea. Relentless artillery and sniper fire across eastern Ukraine has since killed more than 470 people and left Western leaders frustrated by repeated mediation failures.
Poroshenko on Friday agreed to crisis talks with rebel commanders and Russia aimed at stemming bloodshed that has also inflamed East-West ties.
Clashes in the economically vital border regions of Lugansk and Donetsk have picked up with renewed vigour since Poroshenko tore up a 10-day ceasefire agreement last week.
His decision was immediately followed by the launch of a "massive" offensive by Kiev that led President Vladimir Putin to warn that Russia had the right to protect its compatriots in Ukraine.
Poroshenko's call for talks yesterday had yet to be confirmed by Moscow or mediators from the Organisation for Security and Cooperation in Europe.
Additional reporting by Reuters