In the first episode of this two part series, Robert Hodierne, an American military journalist pieces together the horror and barbarism that swept through the village of My Lai 40 years ago.
He reconstructs the events that led up to that day with exclusive archive recordings from the US Army's own investigation into the massacre.
He also speaks to surviving victims and to some of the perpetrators of that historic day.
Massacre at 'Pinkville' The Vietnam war was America's attempt to stop Communists from toppling one country after another in South East Asia.
The US fought there from the early 1960s until 1975. It became America's longest war.
By 1968 there were nearly half a million US troops in Vietnam and more were being hurriedly drafted in to fight.
Most of the men sent into battle in My Lai were very inexperienced and very few of them had seen combat. It was an unconventional war where the enemy wasn't clear - everybody and everything that moved was considered a target.
My Lai was a search and destroy mission - everything from housing and food to people was to be wiped out.
The operation lasted four hours and in that time, US troops had sustained one death and eight injuries.
In contrast 504 villagers were murdered and, in some cases, raped and mutilated.
The operation was touted as a success by the US military and the truth of what really happened remained a secret for a whole year.
The real truth As misgivings about the Vietnam war grew, news of what happened at My Lai gradually began to surface.
The US Army then ordered its own investigation into the massacre, it was called 'The Peers Inquiry'.
In the second part of the My Lai Tapes, you can hear, for the first time, the recordings of the US Army's internal inquiry into the massacre.
The tapes lay forgotten for nearly 40 years until they were tracked down by the British journalist Celina Dunlop, who spent two years trawling through the national archive near Washington.
The Peers Inquiry proved that US soldiers raped and killed hundreds of civilians. It showed just how badly trained and ignorant many of the young men were about the proper treatment of civilians during war.
The conclusions of the inquiry went on to make important and lasting recommendations about how soldiers should be trained in the laws of war.
The My Lai Tapes - Part Two In 1969, almost a year after the atrocities in My Lai, the US Army were so concerned about the rumours of a cover-up of the massacre, that an internal inquiry was ordered.
It became known as 'The Peers Inquiry'.
In the second part of this series, Robert Hodierne, an American military journalist looks at the investigation in detail.
In this programme youcan hear for the first time, the actual recorded testimonies of soldiers, senior officers, chaplains and journalists.
The tape recordings from the Peers Inquiry were tracked down only recently by the British journalist Celina Dunlop.
These recordings provide crucial evidence about this notorious event - a turning point in the Vietnam War.
The Peers Inquiry The Inquiry was led by General William Peers and took place behind closed doors in the basement of the Pentagon from December 1969 to March 1970.
More than 400 witnesses were questioned under oath - everyone from foot-soldiers to the Division Command was interviewed.
Transcripts were made of every word and 400 hours were recorded.
The Inquiry ended on March 14th 1970, nearly 2 years to the day after the My Lai Massacre. It proved that US soldiers raped and killed hundreds of civilians in not just one but three villages that day.
It also proved that two companies, not only the infamous Charlie Company, were involved. It showed just how badly trained and ignorant many of the young men were about the proper treatment of civilians during war.
The Peers Inquiry went on to make important and lasting recommendations about how soldiers should be trained in the laws of war - issues that still resonate in Afghanistan, Iraq and other conflicts today.
If you want to download them just follow this link (part one) and this one (part two). Click on the three dots on the left side of the player to find the download button and save it to somewhere like the desktop of the computer you are using. From there you can listen to it or load it onto your music player (your smartphone, tablet, i-pod, or any mp3 player.
Here are the source web pages (you can also download directly from these):