On Friday more than 1,000 people gathered to remember the victims of the most notorious episode in modern U.S. military history.

Some 504 unarmed civilians were butchered by American soldiers on March 16, 1968 in Son My, Quang Ngai Province, making it one of the worst recorded U.S. war crimes committed in the 20th century.

Among them were 182 women - 17 of whom were pregnant - and 173 children.

Soldiers of Charlie Company were sent on what they were told was a mission to confront a crack outfit of their Vietcong enemies.

They met no resistance - but their commander ordered them to start shooting villagers. 

The brutal killing, which lasted three or four hours, came to be known in the West as the My Lai Massacre.

Do Ba was 9 when American soldiers came to his house and rounded up him, his mother and three siblings and took them to a drainage ditch. 

His mother and siblings were murdered, and he was left wounded, covered in blood and buried under bodies.

He played dead, fearing the soldiers would return to kill him, but was rescued by a U.S Army helicopter crew that landed amid the massacre and halted the violence.

'Twenty years ago, I still harbored hatred against the American soldiers who killed my mother, brothers and sister,' he said.

'But now after 50 years as Vietnam and the United States together developed their relations, people set aside their pain and suffering to build a better society.'