In 2018, Milley was involved in deciding whether the Army would publish a controversial study on the Iraq War.
Milley reportedly decided he wanted to read the two-volume, 1,300-page, 500,000-word document before making a decision.
Milley also directed that an external panel of scholars review the work.
After the panel returned glowing reviews on the study, including one that described it as "the gold standard in official history", Milley continued to delay publication so he could review it further.

In September 2018, Secretary of the Army Mark Esper and other Army officials decided to distance themselves from the study by casting it "as an independent" work of the authors, instead of being described as a project by the Chief of Staff of the Army's Operation Iraqi Freedom Study Group.
When confronted by a journalist from The Wall Street Journal in October 2018, Milley reversed these decisions, ordering the study published officially and with a foreword from himself.
He said the team who wrote the study "did a damn good job", the study itself was "a solid work", and that he aimed to publish the study by the holidays (2018).

Within days of this revelation, two members of Congress who sit on the House Armed Services Committee (Reps.
Jackie Speier, D-California, and Ruben Gallego, D-Arizona) sent a letter to Army leaders expressing their anger over the delay.
In a press release accompanying the letter to Milley and Esper, Speier said, "This is simply the Army being unwilling to publicly air its mistakes.
Our military, Congress, and the American people deserve nothing less than total transparency on the lessons the Army has identified so that we may use those lessons to avoid costly, and too often deadly, mistakes of the past."
The two-volume study was published January 17, 2019.
In 2018, Milley was involved in deciding whether the Army would publish a controversial study on the Iraq War. Milley reportedly decided he wanted to read the two-volume, 1,300-page, 500,000-word document before making a decision. Milley also directed that an external panel of scholars review the work. After the panel returned glowing reviews on the study, including one that described it as "the gold standard in official history", Milley continued to delay publication so he could review it further.
In September 2018, Secretary of the Army Mark Esper and other Army officials decided to distance themselves from the study by casting it "as an independent" work of the authors, instead of being described as a project by the Chief of Staff of the Army's Operation Iraqi Freedom Study Group. When confronted by a journalist from The Wall Street Journal in October 2018, Milley reversed these decisions, ordering the study published officially and with a foreword from himself. He said the team who wrote the study "did a damn good job", the study itself was "a solid work", and that he aimed to publish the study by the holidays (2018).
Within days of this revelation, two members of Congress who sit on the House Armed Services Committee (Reps. Jackie Speier, D-California, and Ruben Gallego, D-Arizona) sent a letter to Army leaders expressing their anger over the delay. In a press release accompanying the letter to Milley and Esper, Speier said, "This is simply the Army being unwilling to publicly air its mistakes. Our military, Congress, and the American people deserve nothing less than total transparency on the lessons the Army has identified so that we may use those lessons to avoid costly, and too often deadly, mistakes of the past." The two-volume study was published January 17, 2019.
Mark Milley