The Army asked the RAND Corporation to do a kind of lessons-learned report on Iraq soon after the invasion. In the summer of 2005, after 18 months of study, “Rebuilding Iraq” was done. RAND submitted a classified version and an unclassified version “hoping that its publication would contribute to the public debate on how to prepare for future conflicts.” Naturally, the report was critical of the conduct of the White House and the Defense Department, since the whole thing had turned into a huge disaster so any useful review would need to be critical of the key people.
Apparently, what happened next was that the Army launched a big effort to suppress the report and keep its findings secret. Because, hey, why seek to inform the public when there are asses to cover?