The last few days have been apocalyptic in Syria. Tens of thousands of civilians fleeing en masse to the border before a government advance. The prospect of mass slaughter yet again. A ban on humanitarian aid crossing the border from Turkey to the three million civilians trapped inside a killbox in the north-west, one of the few remaining pockets outside government control, under bombardment from machine guns and fighter jets. The city of Maarat Al Numan destroyed and abandoned. Collective, global silence and inaction.

It is heartbreaking but entirely in character for a decade in which every international norm of conduct and warfare has been systematically destroyed.

Ten years ago, Syrian President Bashar Al Assad was full of confidence, declaring in a Wall Street Journal interview that the uprisings that had swept other Arab countries could not happen in Syria because the government was in tune with its citizens.

This apparent hold over citizens was of course maintained with an iron fist and an extensive and pervasive network of informants, security and intelligence agencies and prisons, a stranglehold on the economy that allowed epic levels of corruption and tight control over every aspect of public life and civil society.

Nevertheless, Mr Al Assad’s Syria was enjoying the fruits of a broader opening with the West and its Arab and Turkish neighbours.

Damascus had succeeded in creating an opportunity to mend ties with the US out of a problem it created – cracking down on terror cells it had allowed across the border into Iraq to fight American troops. With increasing trade ties, diplomatic outreach and efforts to isolate Iran, Syria’s first couple, Bashar and Asmaa Al Assad, holidayed with Turkey’s president Recep Tayyip Erdogan and attended Bastille Day celebrations with the Sarkozys in France.

Their charisma shone through as they spoke at ease to western reporters about democratic aspirations and dined with the masses in popular Aleppan and Damascene eateries.

It was all a mirage. The decades of Baath party decrepitude, brutality and economic mismanagement had stunted the country. Everyone had a story about a close relative forcibly disappeared in early morning Mukhabarat raids carried out by intelligence agencies. Inequality worsened as agricultural communities fell into ruin and migrated to the cities.

Mohammed Mohiedin Anis, or Abu Omar, 70, smokes his pipe as he sits in his destroyed bedroom listening to music on his vinyl player, gramophone, in Aleppo's formerly rebel-held al-Shaar neighbourhood. (Photo by JOSEPH EID / AFP)

The spark for the war was the detention in 2011 of teenagers who scrawled an anti-Assad slogan on their school wall. Their arrest and the government’s insults in response sparked a cycle of government violence, followed by civilian protest that quickly spread around the country.

It did not have to be this way. Few initially demanded the outright overthrow of the regime, hoping instead to coax Mr Al Assad into instituting reforms.

He met them with renewed brutality, a refusal to engage in serious dialogue that endures to this day and an amnesty that included releasing convicted terrorists in an effort to militarise the opposition and present a choice to the international community – the president or an extremist onslaught.

The rest is bloody, atrocious history. The UN eventually stopped counting the dead, then standing at 400,000, in 2016. The numbers have almost certainly exceeded half a million.

The UN eventually stopped counting the dead at 400,000

Half the country's population was displaced, most inside Syria, many forced to abandon their homes several times in the course of the nine-year war. The millions who fled abroad profoundly altered their neighbouring countries’ character and politics, and those who braved the seas to European shores, fleeing for the sake of their lives and their children’s, were used as a scaremongering tactic by populist leaders across the globe to propel a resurgence of the far right in European and American politics.

This profound shift ushered in tectonic changes and realignments, both abroad and regionally, as Moscow took up the mantle abandoned by a retreating Washington and intervened in the war to save Mr Al Assad from what at the time seemed inevitable defeat. Turkey, incensed by American reliance on Kurdish militias with aspirations for statehood, essentially abandoned its alliance with Nato in favour of close co-operation with Russia, further undermining the post-Second World War order.

A convoy of people fleeing from Maarat Al Numan in northern Idlib. Mahmoud Hassano / Reuters

ISIS took advantage of the power vacuum and profound injustices of the war to establish a so-called state spanning parts of Syria and Iraq, a project laced with atrocities of such grave barbarism as systematic enslavement and mass rape of the Yazidi minority, the exile of Christians from their homeland and the murder and execution of thousands of civilians in manifold horrific ways.

All the while, Syria was being systematically destroyed. The regime and its allies undertook scorched-earth tactics of besieging opposition areas; barrel-bombing them and advancing methodically rendered those areas uninhabitable.

Syria needs at least $200 billion in reconstruction costs, possibly double that, aid that is blocked by western countries due to the absence of political reforms.

These violations are numerous but they are worth elucidating because they show how far we have fallen

But perhaps Syria’s enduring legacy lies in how it has systematically dismantled the international rules-based order. Over a decade of warfare and destruction, every international norm that was once thought of as sacrosanct has been violated with a defiance that once defied belief, until it became par for the course. It is a stark contrast to the message the world emerged with from the genocides in the former Yugoslavia and Rwanda – a mantra of “never again” uttered in the halls of international tribunals.

Instead, over time, cycles of atrocity followed by outrage and impotence chipped away at the tenets we had decided constituted civilised conduct in warfare and affairs of state. Bit by bit, our humanity was chipped away.

These violations are numerous but they are worth elucidating because they show how far we have fallen. Chemical weapons were repeatedly used against civilians in a largely successful effort to terrorise them into submission, with no meaningful retribution. Starvation sieges were used repeatedly as a weapon of war by Mr Al Assad and his allies in the campaign to reclaim rebel-held territory.

Deserted Maarat Al Numan in north-western Idlib province. Omar Haj Kadour / AFP

Systematic bombing of civilians with inaccurate weapons like barrel bombs, whose use constitutes de facto war crimes, large-scale arbitrary detention and forced disappearance of tens of thousands of civilians, the targeting of hospitals and the use of humanitarian aid and UN assistance as political tools have continued to make life unbearable for civilians.

The next few years are hard to predict in Syria, precisely because the conflict destroyed all the myths we have cultivated about ourselves – how empathetic we are, how seriously we take our responsibility as an international community to protect civilians, our collective belief in justice being served and in a shared destiny.

Syria destroyed all of that in the course of crushing the dreams and rights of an entire people to live in dignity, peace and prosperity.

Even as the wrangling over the ashes continues, the legacy of the last decade will endure. Syria has carved the epitaph of the collective conscience of the international community.

Kareem Shaheen is a former Middle East correspondent, now in Canada