US soldiers killed 504 innocent Vietnamese villagers at My Lai in Vietnam on March 16th 1968.

Women and children were raped, cattle were slaughtered, houses burned and crops destroyed.

It became known as the 'My Lai massacre' and its significance still resonates today.

Only one solider, Lt William Calley, was prosecuted for what happened in My Lai.

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 you can 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 last year by the British journalist Celina Dunlop.

These recordings provide crucial evidence about this notorious event - a turning point in the Vietnam War.

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. Show less