Publication was delayed six months so that Gen. George W. Casey Jr., the current Army chief of staff and former top commander in Iraq, could be interviewed and senior Army leaders could review a draft.

The study’s authors were instructed not to shy away from controversy while withholding a final verdict on whether senior officials had made mistakes that decisively altered the course of the war, said Col. Timothy R. Reese, the director of the Combat Studies Institute at Fort Leavenworth, Kan., who, along with Donald Wright, a civilian historian at the institute, oversaw the volume’s preparation.

Even so, the study documents a number of problems that hampered the Army’s ability to stabilize the country during Phase IV, as the postwar stage was called.

“The Army, as the service primarily responsible for ground operations, should have insisted on better Phase IV planning and preparations through its voice on the Joint Chiefs of Staff,” the study noted. “The military means employed were sufficient to destroy the Saddam regime; they were not sufficient to replace it with the type of nation-state the United States wished to see in its place.”

For his part, General Franks said through an aide that he had covered Iraq decisions in his book and had not seen the forthcoming report.

The report focuses on the 18 months after President Bush’s May 2003 announcement that major combat operations in Iraq were over. It was a period when the Army took on unanticipated occupation duties and was forced to develop new intelligence-gathering techniques, armor its Humvees, revise its tactics and, after the Abu Ghraib prison scandal, review its detention practices.

A big problem, the study says, was the lack of detailed plans before the war for the postwar phase, a deficiency that reflected the general optimism in the White House and in the Pentagon, led by then-Secretary of Defense Donald H. Rumsfeld, about Iraq’s future, and an assumption that civilian agencies would assume much of the burden.