Leading the My Lai Investigation: Peers led the most comprehensive investigation into the My Lai massacre, interviewing over 400 witnesses and reviewing thousands of documents. His commission produced a report that documented both the scope of the massacre and the systematic cover-up by the chain of command, from company level through division headquarters.

Recommendation of 30 Court-Martials: The Peers Commission recommended that 30 individuals face charges, including Major General Samuel Koster (the Americal Division commander) and Brigadier General George Young. The recommendations covered murder, assault, rape, dereliction of duty, and cover-up charges spanning the full chain of command.

Documentation of the Cover-Up: The Peers Commission documented how the cover-up of the massacre extended from the company level through the brigade and division levels. Officers at every level either actively participated in suppressing information or failed to investigate obvious evidence of the atrocity, including the massive discrepancy between claimed enemy casualties and weapons recovered.

Frustration with Failed Accountability: Peers was deeply frustrated that only one of the 30 individuals he recommended for prosecution was ultimately convicted. He later wrote "The My Lai Inquiry" expressing his dismay at the military justice system's failure to hold the chain of command accountable for both the massacre and the cover-up.

Establishing the Full Scope of the Massacre: The Peers Commission established that the massacre was far more extensive than initially reported, documenting between 175 and 400 individual deaths (with some estimates reaching higher). The commission also documented sexual violence, destruction of property, and the killing of livestock as part of the systematic attack on the village.

Integrity Under Political Pressure: Despite political pressure to minimize the findings or limit the scope of the investigation, Peers insisted on a thorough and honest inquiry. His refusal to whitewash the results demonstrated that institutional integrity was possible even under intense political pressure.