How will history remember the last years in Aleppo? The proud and storied jewel of northern Syria, one of the oldest continuously inhabited cities in the world, was a vibrant commercial hub until war began to tear it apart in 2012.

When the uprising against President Bashar al-Assad reached Aleppo that year, he was determined to do all it would take to prevent Syria's second city from slipping from his grasp. The regime's capture of eastern Aleppo - which rebels had made their stronghold since summer 2012 - last December shifted the military balance in Mr Assad's favour. But at what cost?

The horrors of Syria's six-year war - and the way it has played out in Aleppo and other parts of the country - have been magnified in this social media age. But coupled with that is the sense that the full scale of what has transpired in Syria - including in the regime prisons and detention centres into which thousands have disappeared - remains unknown.

In the case of Aleppo, competing narratives - for Mr Assad, it was a battle against and 'liberation' from what he calls terrorists; for his opponents, it was the defence and 'fall' of a key rebel stronghold - have obscured the picture, particularly given that few journalists were able to access the city last year.

This week, however, the UN's Commission of Inquiry on Syria released a report that offered some clarity on what unfolded in Aleppo between July 21 last year, when regime forces - with the help of Russian warplanes - started besieging eastern Aleppo, and December 22, when they took full control of the city.

"The scale of what happened in Aleppo is unprecedented in the Syrian conflict," said the commission's chairman, Paulo Pinheiro. "Much of Aleppo, once Syria's biggest city and its commercial and culture centre and a Unesco World Heritage site, has been reduced to rubble."

Drawing on the testimony of 291 eyewitnesses and using satellite imagery, medical reports and forensic evidence, the commission's report details violations by all factions involved in the protracted battle for Aleppo. It describes how at least 5,000 pro-Assad fighters had encircled the rebel enclave of eastern Aleppo in an effort to force opposition forces to "surrender or starve". A deal between the warring parties to evacuate the area in the final weeks of the offensive gave civilians there no option to remain, and the UN commission concluded the conditions of that agreement in fact amounted to "the war crime of forced displacement".

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Both sides carried out indiscriminate attacks in densely populated residential areas, with opposition forces shelling government-held districts. According to the report, some anti-Assad fighters shot civilians to prevent them from fleeing and used them as human shields.

A deadly and sustained aerial bombardment of the city was key to the regime's efforts, with toxic chlorine bombs air-dropped "throughout 2016". The report also detailed the regime's "pervasive use" of cluster munitions in civilian areas, which amounted to a war crime.

"For months, the Syrian and Russian air forces relentlessly bombarded eastern Aleppo city as part of a strategy to force surrender," Mr Pinheiro said. "The deliberate targeting of civilians has resulted in the immense loss of human life, including hundreds of children."

The commission said it had concluded that Syrian warplanes targeted hospitals on at least two occasions. Human rights groups have documented airstrikes on medical facilities and bakery queues in eastern Aleppo since 2012.

The UN report also accused the Assad regime of a "meticulously planned and ruthlessly carried out" airstrike on a UN and Syrian Red Crescent humanitarian convoy in rural western Aleppo in mid-September. The attack, which killed 14 aid workers, prompted outrage at the time, but the Syrian government and Russia denied responsibility for it. "By using air-delivered munitions with the knowledge that humanitarian workers were operating in the location, Syrian forces committed the war crimes of deliberately attacking humanitarian relief personnel, denial of humanitarian aid, and attacking civilians," the report said.

The UN commission says it is ready to share its list of suspects with a recently formed UN panel tasked with preparing cases towards prosecuting those responsible for war crimes and crimes against humanity in Syria.

One of the commission's members, Carla Del Ponte, who previously acted as chief prosecutor of the international criminal tribunals for Rwanda and the former Yugoslavia, told media that Mr Assad had to be held to account.

"That's six years now that he has been responsible for a large number of civilian deaths. We must bring Assad to justice. He is one of the worst criminals," she said. "What we have seen here in Syria, I never saw that in Rwanda, or in former Yugoslavia, in the Balkans. It is really a big tragedy."

A tragedy that continues still.

Irish Independent