Earlier this year, the U.S. Army published two volumes that amount to the most comprehensive official history of the Iraq war. They cover the conflict’s most important episodes: the U.S. invasion in 2003, the death spiral into civil war that took shape in the aftermath, the more hopeful period that began with the surge of U.S. forces in 2007, and the withdrawal that saw the last U.S. forces leave Iraq at the end of 2011.

Blandly titled The U.S. Army in the Iraq War and based on 30,000 pages of newly declassified documents, the study recounts a litany of familiar but still infuriating blunders on Washington’s part: failing to prepare for the invasion’s aftermath, misunderstanding Iraqi culture and politics and sidelining or ignoring genuine experts, disbanding the Iraqi army and evicting Baath Party members from the government, ignoring and even denying the rise of sectarian violence, and sapping momentum by rotating troops too frequently.

Years in the making and admirably candid, the study has largely been ignored by the media and the policy community. That may be because of its daunting length and dry, “just the facts” narrative.

Or because some understandably prefer independent accounts to authorized after-action reports. Or because, compared with other major conflicts in U.S. history, so few Americans experienced this one firsthand.

Or because the study declines to focus on more timely and contested questions, such as whether it was ever in the realm of possibility to invade a large and diverse Middle Eastern country—one that posed no direct threat to the United States—at an acceptable cost. But the study also comes at a time when many of the supposed lessons of Iraq are increasingly contested, with significant implications for a debate that is raging between and within both major political parties over the most consequential foreign policy choice any country faces: when and how to use military force.