Let's start at the beginning.

On March 16, 1968, soldiers from B and C Company, 1st and 3th Battalions, 3rd and 20th Infantry Regiments, 11th Infantry Brigade, 23rd Infantry Division commit a massacre in two South Vietnamese hamlets, a war crime that goes under the collective name the My Lai massacre.

Six months after the massacre, Specialist Tom Glen, a mortarman in the 11th Infantry Brigade, sends a letter to General Creighton Abrams (who had just arrived to take command after the departure of General William Westmoreland). The letter is not about the My Lai massacre. Glen did not witness the event and only heard about it second-hand. The letter instead focused on what Glen saw as a widespread pattern of American aggression, hate, and brutality towards South Vietnamese civilians. The most quoted part of the letter is the conclusion, which states the following:

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 and the Geneva Conventions, perhaps be eradicated.

Major Colin Powell of the 11th Infantry Brigade, 23rd Infantry Division, is given the task of investigating the claims made by Glen in his letter. The subsequent investigation was carried out quite poorly, something attributed to the fact that he was likely following strict procedural steps in investigating the matter. Powell did not, for example, talk to Glen about the content of his letter. The resulting conclusions drawn by Powell were shallow. Powell claimed that although there were certainly isolated cases of maltreatment of South Vietnamese civilians, it was not systematic in the 23rd Division, ultimately making the claim that "that relations between American soldiers and the Vietnamese people are excellent."

This was not actually the case, as the example of the My Lai massacre and other atrocities carried out by American forces in South Vietnam make very clear. Yet for Major Powell, this is where it ends. He has investigated the matter, he writes his response, and denies Glen's claims. As Howard Jones convincingly argues, Powell just wrote what his superiors wanted to hear. Did Powell know that he was lying? Possibly, seeing as he had witnessed brutality towards South Vietnamese civilians himself. However, it might very well just have been like he considered it in his own 1995 autobiography: "The kill-or-be-killed nature of combat tends to dull fine perceptions of right and wrong."

What did Powell know about My Lai? In his autobiography, Powell claims to not even have known about the My Lai massacre until 1970. However, Powell was interviewed by Colonel William D. Sheehan, who was investigating the massacre, in May 1969. He was asked very specific questions about the unit involved in the massacre, and while Powell kept claiming that he did not hear about anything since he was not even in South Vietnam at the time, it seems hardly credible that he would not even have heard a rumor. His answers during the interview, together with his investigation into the Glen letter, should be seen as connected.

Tom Glen's letter was forgotten after the conclusion of Powell's investigation, stashed away in the National Archives until found decades later. By then, Major Powell had become General Powell. In 1992, Michael Bilton and Kevin Sim releases a documentary and book on the My Lai massacre, Four Hours in My Lai, that included the aforementioned letter for the first time. This brought the letter back to the forefront within the context of My Lai.

In 1995, journalist Charles Lane makes the accusation that Powell contributed to the cover-up of My Lai in an article for New Republic titled "The Legend of Colin Powell". This actually begins a debate about the culpability of Powell in the cover-up of My Lai. While this debate raged in 1995 through 1996, nothing conclusive ever came out of it. Indeed, that might be why it has reappeared over 25 years later.

What can we say about Powell's role in the cover-up of My Lai? We can conclusively say that he did not play a leading part in the cover up. In fact, as journalists Robert Parry and Norman Solomon wrote in 1995, Powell played a very peripheral part in the cover up. Yet there's no doubt that he did play a small part in the My Lai cover up and in the cover up of American atrocities at large.

Primary and secondary sources:

My Lai: Vietnam, 1968, and the Descent Into Darkness by Howard Jones.

Four Hours in My Lai by Michael Bilton and Kevin Sim.

Colin Powell: Imperfect Patriot by Jeffrey J. Matthews.

My American Journey by Colin Powell.

"The Legend of Colin Powell" by Charles Lane. New Republic. April 17, 1995.

"The Very Model Of A Political General" by John Barry, Newsweek. September 11, 1995.

"Behind Colin Powell's Legend" by Robert Parry and Norman Solomon. The Consortium. 1996.

The original Glen letter can be found in the National Archives. See Tom Glen to General Creighton Abrams, November 27, 1968, My Lai Investigation Files.

I don't know the politics or why this subreddit is like it is now, or why it was the way it was when I used to make jokes about to my S.O. about never getting any real answers.

Tonight I've checked in on two disparate subjects that interest me and came away smarter and impressed with the quality of the answers, the writing, and the comments in general.

I don't know who to thank. The moderators possibly.

Regardless, THANK YOU!

An informative and even-handed answer. Thank you.