“I’ve never seen anything like it, beyond description.”

Fares al-Jundi, a doctor at a nearby hospital treating the victims of Syria’s alleged chemical attack said as he described the horrifying scenes.

“I believe this horrible memory will stay with me for the rest of my life,” he added.

On April 4, residents of Khan Sheikhoun, the northern Syrian town, while sleeping were gassed in what is feared to be the deadliest chemical attack in the country in years.

But this is not the first time chemical weapons have been used in conflict, though we hope it’s the last.

Rediff.com takes a look at times these deadly weapons have been used.

Click on the dates to read more.