By Drew Griffin and Jessi Joseph, CNN Special Investigative Unit

It will go down in history as one of the U.S. military's worst battles in Afghanistan. And according to the families of the soldiers who died there, the history written by the U.S. Army is biased and inaccurate.

Relatives of those killed in Wanat, at a combat outpost in the rugged mountains of northeastern Afghanistan, say the Army is covering up mistakes made by the dead mens' commanders and placing blame on a junior officer who was simply following orders.

The 9 who died at Wanat

"My personal opinion is that the Army is trying to protect their institution," said Dave Brostrom, the father of 1st Lt. Jonathan Brostrom, who was killed in the battle. "It’s a lot easier to blame a dead lieutenant than it is to blame the chain of command."

The July 13, 2008 battle at Wanat, near the Pakistani frontier, was one of the bloodiest since the Afghan war began in 2001. A U.S. force of 49, plus 24 Afghan troops, desperately fought off an attack by some 200 Taliban fighters, calling in air strikes barely 30 feet from their own positions during the struggle.

The platoon, in close combat with Taliban fighters, repelled the enemy after nearly four hours of intense fire at a cost of nine Americans dead and 27 wounded.

A military investigation that followed, led by Marine Lt. General Richard Natonski, blamed the deaths in part on dereliction of duty by superior officers of the 173rd Airborne Brigade and called for career-ending reprimands for company, battalion and brigade commanders up the chain.

Those recommendations were approved by Gen. David Petraeus, then chief of U.S. Central Command, which oversees American forces in the Middle East and Afghanistan.

Army Secretary James McHugh then tasked Gen. Charles Campbell, the chief of the Army's Forces Command at the time, with reviewing Natonski’s investigation and taking appropriate action regarding the recommended letters of reprimand. After reviewing Natonski’s investigation and meeting with the chain of command, Gen. Campbell concluded that the officers were neither negligent nor derelict and rescinded the letters of reprimand.

Then the Army published their study of the battle – which, according to Dave Brostrom, put a large part of the blame on his son, who commanded the airborne infantry platoon at Wanat.

That report by the Army's Combat Studies Institute is now the official history of the battle, and Brostrom - a retired colonel who is about to send his second son into the service – says the report needs to be re-written.

Up until the day of the battle, Brostrom said, his son was sending warnings up his chain of command that things were not well in Wanat.

Video taken by the soldiers of 2nd Platoon, Chosen Company showed crudely dug defensive positions, a few sandbags and the enemy easily visible within shooting range. The Afghan contractors that were supposed to provide heavy equipment and engineers never showed up to help build an actual defensive position, and troops were left to basically dig into the ground in 100-degree heat while water supplies ran low.

Natonski’s investigation found the officers at the battalion and brigade levels had become preoccupied with other matters - including a visit from Adm. Mike Mullen, Chairman of the Joint Chiefs of Staff. The investigation also found the battalion and brigade commanders failed to heed warnings that the Wanat outpost lacked construction equipment and supplies, was struggling with a shortage of drinking water and was undermanned days before the battle.

Worse, the Natonski investigation found warnings being sent by the platoon of an increasing buildup of insurgents in the area were either ignored or failed to make their way up the chain of command.

General Campbell’s review of the battle excuses the commanding officers' inattention to a platoon under threat, concluding that due to the busy schedules being kept by the commanders and other troop engagements in the area, "It seems reasonable that these officers' attentions were devoted to more pressing matters."

It was a complete reversal from what Natonski and Petraeus had found in their original report. And Petraeus told the Senate Armed Services Committee last summer that he disagreed with Campbell’s decision not to punish commanders involved.

“I respect his view in this particular case. I support the process,” Petraeus testified. ”But I did not change the finding that I affirmed after the investigating officers provided it to me."

A source close to the Army’s investigation said the commanders were negligent in the planning, negligent on the supervision and negligent in getting the proper resources to the soldiers who were in harm's way.

"If everyone did business this way," the source told CNN, "we'd be losing a lot more lives in Afghanistan and Iraq."

Sen. Jim Webb, D-Virginia, asked Army Secretary James McHugh to include the higher commands shortcomings in the Army’s official version of events at Wanat, a report that is intended to be used as a learning tool to train soldiers.

"The study's failure to assess decisions made by more senior leaders makes this accounting a flawed and biased 'implement of learning,' " wrote Webb, a member of the Senate Armed Services Committee and a highly decorated Vietnam veteran.

In a meeting between Army officials and several family members of the nine dead soldiers, Campbell explained his decision not to reprimand the commanding officers was to protect future combat missions.

"I informed the Secretary of the Army of the action that I took,” General Campbell told the families. “And my determination is that the officers listed in the report had exercised due care in the performance of their duties."

Brostrom has asked the Army to pull the Combat Studies Institute report, which blames his son for poor placement of defensive positions at the combat outpost in Wanat. He maintains his son was simply following orders, and died carrying out a poorly planned mission by the command staff.

In a statement to CNN, the Army maintains that they have, “thoroughly investigated and shared all findings with family members, Congress, the media and the Army at large.”

The Army wrote that they understand there are still differing views among those who have reviewed their investigation and published study but say they have tried to be transparent, “Any suggestion that the Army has been less than forthright in this matter is simply not true.”

But Dave Brostrom believes the Army is less concerned about his son and more concerned about protecting their institution.

"It's more important than lessons learned and protecting our soldiers," he said.

Brostrom has asked the Department of Defense’s Inspector General to review whether the higher command, originally found derelict of duty, had an undue influence on the re-writing of history.