The Islamic State in Iraq and Syria’s (ISIS) single bloodiest operation to date — the execution of over 700 Shaitat tribesman over a three day period in August — received little to no coverage from western media outlets, The Washington Post reports.

The massacre targeted all men and boys older than 15, and was in response to an uprising.

After years of rejecting the central Syrian government, the Shaitat tribe was forced to sign a July truce with ISIS after jihadist forces captured the massive supply of U.S. munitions stockpiled in the Iraqi city of Mosul.

When ISIS descended upon the Syrian town of Abu Hamam, “we realized we had no hope. We were surrounded. We wanted to save our people,” said one Shaitat fighter.

But the uneasy cease-fire between the Sunnis and ISIS’s extreme jihadist faction quickly decayed into violence.

When ISIS militants publicly beheaded a Shaitat man who had fired on one of their patrols, local residents overpowered the small garrison of terrorist fighters and forced them from the town, only to see them return with reinforcements and artillery from Mosul.

After shelling Abu Hamam for days, ISIS forces once again captured the town and began systematically executing every Shaitat male over the age of 15.

“A photo essay on an Islamic State blog boasted of the different ways tribesmen were killed, including beheadings, mass shootings and a crucifixion,” the Post reports. “A video shows how the militants lined up scores of captives on a road, their hands bound, then set about clumsily decapitating them, one by one.”

“Using fake identity cards or escape routes honed during their battle against the [Syrian] government,” the article continues, some Shaitat succeeded in fleeing across the border into Turkey.

Months after the massacre, Shaitat survivors living in Reyhanli, Turkey haven’t forgotten the atrocity,

“We are tribal people,” former-Shaitat rebel Abu Salem told the Post. “We will never forget to avenge, but we will do it by ourselves, in our own way. We won’t take any help from anyone.”