This report contains images some readers may find distressing
Now the forces of President Bashar Assad and his Russian allies are focused on Idlib - one of the last remaining rebel strongholds in Syria - inflicting suffering and death on thousands on a similar scale.
On Wednesday, Turkey's President Erdogan threatened to use force to stop the Syrian advance, ever closer to his border.
Despite a ceasefire in Idlib - the bombardment of the city by government forces has continued in recent weeks.
In the last month, 1,500 people have been killed.
More than half a million people have also been forced to flee, 80% of them women and children.
With the border with Turkey closed to them - many have been left with nowhere to escape.
A recent attack killed seven members of Fida Agha's family – he gathered the dead including his mother, his wife and two children.
The youngest was just one month old.
Mr Agha said his family were packing up their home when it was struck - they were about to leave for a safer area but never got the chance.
Two senior American doctors of Syrian background sent ITV News their footage from their recent visit into Idlib and the surrounding camps.
The President of the Syrian Medical Association, Dr Mufaddal Hamadeh, told ITV News of nine-year-old Kutaiba who lost 10 of his 11 siblings in an attack which left him hospitalised with shrapnel wounds, with one piece going in to his brain.
The UN has called for an cessation of hostilities and agencies are overwhelmed.
President of the International Rescue Committee David Miliband said the situation has left civillians bearing the brunt of the "unendless civil war".
"The truth is there is no plan, no strategy, no international engagement, and that's giving licence to Russian bombers and to President Assad to pursue a policy that really puts the civillians at the severe sharp end of an unendless civil war," the former Labour MP said.
A spokesperson for Secretary-General António Guterres said he is "deeply concerned by the ongoing military escalation in northwest Syria and calls for an immediate cessation of hostilities.
"He reaffirms that attacks on civilians and civilian infrastructure, including on healthcare and educational facilities, are unacceptable.
"Military operations of all parties, including actions against and by designated terrorist groups, must respect the rules and obligations of international humanitarian law, which include the protection of civilians and civilian objects.
"The Secretary-General reiterates that there is no military solution to the Syrian conflict.
"The only path to stability is a credible and inclusive UN-facilitated political solution."