The Coverage and Investigation

The coverage of the My Lai Massacre has changed since it was initially released to the public. Attempts to coverup or downplay the massacre occurred soon after the events.

The initial reports stated that "128 Viet Cong and 22 civilians" were killed during a "fierce fire fight". 

General William Westmoreland gave the perpetrators praise by saying "outstanding job". 

The press briefing on March 16, 1968, known as the  "Five O'Clock Follies" included a passage on the event: "In an action today, Americal Division forces killed 128 enemy near Quang Ngai City. Helicopter gunships and artillery missions supported the ground elements throughout the day."

The initial responses all seem like the U.S. military is doing its job and there were unfortunate casualties of war. 

Colonel Henderson began investigations of the event under Brigadier General George H. Young. His investigations concluded that there were about 20 civilians killed in the operation. 

The truth began to come to light when Tom Glen, a soldier in the 11th Infantry, wrote to General Abrams, saying that "It would indeed be terrible to find it necessary to believe that an American soldier that harbors such racial intolerance and disregard for justice and human feeling is a prototype of all American national character; yet the frequency of such soldiers lends credulity to such beliefs. ... What has been outlined here I have seen not only in my own unit, but also in others we have worked with, and I fear it is universal. If this is indeed the case, it is a problem which cannot be overlooked, but can through a more firm implementation of the codes of MACV (Military Assistance Command Vietnam) and the Geneva Conventions, perhaps be eradicated." (18)

Colin Powell investigated Glen's letter and "refuted" it. 

In March 1969, Specialist 5 Ronald L. Ridenhour, a former door gunner from the Aviation Section, Headquarters Company of the 11th Infantry Brigade, sent a letter to 30 members of congress asking for an investigation of the My Lai incidents. Most of the congressmen ignored Ridenhour's request. 

On November 12, 1969, investigative journalist Seymour Hersh figured out the story due to interviews with Calley.

On November 20, Time, Life and Newsweek magazines all covered the story.

CBS televised an interview with Paul Meadlo afterwards. 

The Plain Dealer (Cleveland, Ohio) published photographs of the deceased. 

After further investigations, General Peers found that: "[The 1st Battalion] members had killed at least 175–200 Vietnamese men, women, and children. The evidence indicates that only 3 or 4 were confirmed as Viet Cong although there were undoubtedly several unarmed VC (men, women, and children) among them and many more active supporters and sympathizers. One man from the company was reported as wounded from the accidental discharge of his weapon. ... a tragedy of major proportions had occurred at Son My." (12)

In July 1969, the Office of Provost Marshal general of the Army began a thorough investigation using Peers Report and Calley was charged with murder and 25 other officers were charged with related crimes. 

In the end, only Calley was convicted.

https://en.wikipedia.org/wiki/William_Calley