Army Lt. Gen. David Petraeus, right, is presented with the Combined Arms Center colors as he takes command of Fort Leavenworth on Thursday from Gen. William Wallace.

Fort Leavenworth ? Lt. Gen. David H. Petraeus, who played a key role for the Army in early phases of the Iraq War and more recently was in charge of training Iraqi forces, is now the top man at Fort Leavenworth.

In a change of command ceremony Thursday, Petraeus took over from Gen. William S. Wallace as commander of the Combined Arms Center and Fort Leavenworth. The new assignment brings him back to the post where he led his class upon graduating from the Command and General Staff College in 1983.

Petraeus, 52, has been in the Army since 1974, and his assignments before Iraq have included tours of duty in Bosnia, Haiti and Germany. He commanded the 101st Airborne Division, which played a major role in the initial invasion of Iraq. It took the central Iraq cities of Najaf, Hillah and Karbala before occupying southern Baghdad. It later went on to take control of the northern region of the country.

Petraeus was then put in charge of training and equipping the Iraqi military, an assignment he finished on Sept. 8. In Washington earlier this month, he said only one of slightly more than 115 Iraqi army and special police battalions had reached a “level 1” rating indicating an ability to operate independently of U.S. forces.

The first shot of a 15-gun salute to Fort Leavenworth's new commander, Lt. Gen. David Petraeus, is fired at the command of Staff Sgt. William Holcomb, left, Thursday during an Assumption of Command Ceremony at Fort Leavenworth.

But Petraeus also said it was not necessary for the Iraqi units to reach the highest level of readiness before U.S. troops can begin to leave Iraq. He said it would be “quite some time” before large numbers of the units reach that level.

Wallace, who now heads the Army’s Training and Doctrine Command at Fort Monroe, Va., was commander of the Army V Corps in the initial combat phase in Iraq. He called Petraeus, who will report to him, an extremely gifted leader and seasoned Army veteran.

“He understands the business of leading and training soldiers for the complications of battlefields,” Wallace said.

“His vision ensures the organization will remain viable,” Wallace said.

Petraeus said the Combined Arms Center is, as advertised, “the gateway to the Army’s future.” The post plays a key role in preparing officers for battle command and tactics.

As commander, Petraeus will oversee Fort Leavenworth’s 3,000 soldiers and 2,500 civilian employees.