Soon after American forces toppled Saddam Hussein in 2003, Gen. Tommy R. Franks surprised senior Army officers by revamping the Baghdad-based military command.

The decision reflected the assumption by General Franks, the top American commander for the Iraq invasion, that the major fighting was over. But according to a new Army history, the move put the military effort in the hands of a short-staffed headquarters led by a newly promoted three-star general, and was made over the objections of the Army’s vice chief of staff.

“The move was sudden and caught most of the senior commanders in Iraq unaware,” states the history, which adds that the staff for the new headquarters was not initially “configured for the types of responsibilities it received.”

The story of the American occupation of Iraq has been the subject of numerous books, studies and memoirs. But now the Army has waded into the highly charged debate with its own nearly 700-page account: “On Point II: Transition to the New Campaign.”

The unclassified study, the second volume in a continuing history of the Iraq conflict, is as noteworthy for who prepared it as for what it says. In essence, the study is an attempt by the Army to tell the story of one of the most contentious periods in its history to military experts — and to itself.

It adds to a growing body of literature about the problems the United States encountered in Iraq, not all of which has been embraced by Army leaders.

Lt. Col. Paul Yingling of the Army ignited a debate when he wrote a magazine article that criticized American generals for failing to prepare a coherent plan to stabilize postwar Iraq.

In 2005, the RAND Corporation submitted a report to the Army, called “Rebuilding Iraq,” that identified problems with virtually every government agency that played a role in planning the postwar phase. After a long delay, the report is scheduled to be made public on Monday.

But the “On Point” report carries the imprimatur of the Army’s Combined Arms Center at Fort Leavenworth. The study is based on 200 interviews conducted by military historians and includes long quotations from active or recently retired officers.

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.

“I can remember asking the question during our war gaming and the development of our plan, ‘O.K., we are in Baghdad, what next?’ No real good answers came forth,” Col. Thomas G. Torrance, the commander of the Third Infantry Division’s artillery, told Army historians.

The allied land war command, which was led by Lt. Gen. David D. McKiernan and which reported to General Franks, did additional work on the postwar phase, but its plan was not formally distributed to the troops until April 2003, when the ground invasion was under way.

Inadequate training was also a factor. Lt. Col. Troy Perry, the operations officer of the First Battalion, 68th Armor Regiment, told Army historians that his unit trained extensively, but not for the sort of problems that it would encounter in setting up “stability operations” for securing Iraq once Mr. Hussein’s government fell.

A fundamental assumption that hobbled the military’s planning was that Iraq’s ministries and institutions would continue to function after Mr. Hussein’s government was toppled.

“We had the wrong assumptions and therefore we had the wrong plan to put into play,” said Gen. William S. Wallace, who led the V Corps during the invasion and currently leads the Army’s Training and Doctrine Command.

Faced with a brewing insurgency and occupation duties that they had not anticipated, Army units were forced to adapt. But organizational decisions made in May and June 2003 complicated that task.

L. Paul Bremer III, who replaced Jay Garner, the retired lieutenant general, as the chief civilian administrator in Iraq, issued decrees to disband the Iraqi Army and ban thousands of former Baath Party members from working for the government, orders that the study asserts caught American field commanders “off guard” and, in their view, “created a pool of disaffected and unemployed Sunni Arabs” that the insurgency could draw on.

Some of General Franks’s moves also appeared divorced from the growing problems in Iraq. Before the fall of Baghdad, Col. Kevin Benson, a planner at the land war command, developed a plan that called for using about 300,000 soldiers to secure postwar Iraq, about twice as many as were deployed.

But that was not what General Franks and the Bush administration had in mind. In an April 16 visit to Baghdad, General Franks instructed his officers to be prepared to reduce forces rapidly during an “an abbreviated period of stability operations,” the study notes.

“In line with the prewar planning and general euphoria at the rapid crumbling of the Saddam regime, Franks continued to plan for a very limited role for U.S. ground forces in Iraq,” the report says.

The next month, General Franks directed General McKiernan, then the senior officer in Baghdad, to leave Iraq, along with the staff of his land war command, which had helped plan the invasion and had overseen the push to Baghdad.

A new headquarters would be established to command the military forces in Iraq and was to be led by Lt. Gen. Ricardo S. Sanchez. He had led the First Armored Division into Iraq before being promoted and picked to succeed General Wallace as the head of the Army’s V Corps, which was to serve as the nucleus of the newly established command.

When Gen. Jack Keane, the vice chief of staff of the Army, learned of the move, he was upset. General Keane had helped General McKiernan assemble his headquarters, which had long been focused on Iraq and had more high-ranking officers than V Corps, which had been deployed from Europe. General Keane assumed that General McKiernan’s headquarters would oversee what was fast becoming a troubled occupation.

“I think we did not put the best experienced headquarters that we had in charge of that operation,” General Keane said in an interview with Army historians. “It took us months, six or seven or eight months, to get some semblance of a headquarters together so Sanchez could at least begin to function effectively.”

General Keane told the historians that he raised his concerns at the time with Lt. Gen. John P. Abizaid, who had been picked to succeed General Franks as the head of Central Command.

“I said, ‘Jesus Christ, John, this is a recipe for disaster,’ ” General Keane told Army historians. “I was upset about it to say the least, but the decision had been made and it was a done deal.”

Asked about the decision to establish a new headquarters, General Franks told Army historians that he had told the Pentagon what was needed and that it was the Defense Department’s responsibility to ensure that the headquarters was rapidly installed.

He said he told the Pentagon leadership that a new headquarters was needed and that it was up to them to “figure it out.”

General Sanchez, who has retired from the Army and recently published a book about his time in Iraq, told historians that his new command was hampered by staff shortages and by the failure to coordinate the transfer of responsibilities to his new headquarters.

“There was not a single session that was held at the command level to hand off or transition anything,” he said.

Summing up the episode, General Wallace told historians that the shift to a new headquarters involved a complicated transfer of responsibilities at a critical time.

“You can’t take a tactical headquarters and change it into an operational headquarters at the snap of your fingers,” he said. “It just doesn’t happen.”

(WASHINGTON — June 29, 2008)