The only journalistic sin worse than disastrously misreporting an important story that turns out to be untrue is disastrously misreporting an important story that is true, so no one believes it anymore.

The end result of Dan Rather’s half-assed September 2004 report on George W. Bush’s already well-chronicled, cowardly, rule-breaking behavior as a young man during the Vietnam War was that Bush, once again, was able to avoid accountability for his conduct, and skated to an election victory over John Kerry, a genuine war hero his lickspittles had successfully smeared as unpatriotic.

So a story that should have taken down a president — a story that was already thoroughly documented, but that the mainstream media had hitherto shied away from as overly partisan — was instead discredited, never to be heard of again. Never, at least, until a very bad movie called Truth came out this month, trying to get us to see Rather (Robert Redford) and his producer, Mary Mapes (Cate Blanchett), as heroic and wronged, rather than grappling honestly with their journalistic failures.

Rather and Mapes had an obligation to make sure their segment for CBS’s “60 Minutes II” on Bush using pull to get into the National Guard instead of going to Vietnam — and then going AWOL for a chunk of what was supposed to be his service — was bulletproof. But it wasn’t even bloggerproof. The “new” documents they got copies of — from a source who was cagey about their provenance — were debunked by a bunch of Internet sleuths. An independent review commissioned by CBS found that the segment “failed to meet” CBS’s “two core principles: accuracy and fairness,” and Rather, Mapes and three other staffers were fired or forced to retire.

Two things are undeniably true about the Bush-AWOL story. One is that its collapse exemplified the Bush magic that somehow imbued him with the aura of competence, intelligence, and leadership and made him oddly invulnerable to obvious criticism — think “The Emperor’s New Clothes” — until it all came crashing down after Hurricane Katrina.

The other truth is that Bush was undeniably a shirker, and smugly AWOL from his safe, cushy National Guard gig at a time when thousands of young men his age were being sent to their slaughter in Vietnam.

That had been clear ever since Walter Robinson, the editor of the Spotlight investigative team at the Boston Globe, extensively reported out the story in May 2000, piecing together an article from available military records that has never been definitively challenged.

The Washington Post in 1999 had raised questions of favoritism and joining the Guard to avoid dangerous duty in Vietnam. But it was the Globe that introduced the missing AWOL year.

Possibly because the Globe had out-reported its bigger colleagues, the story didn’t get picked up by the elite national outlets. When Democrats tried to bring it up again on the eve of the election, the New York Times pooh-poohed it under an instant classic of false-equivalence headline: “Bush’s Guard Attendance Is Questioned and Defended.” A “review of records by the New York Times indicated that some of those concerns may be unfounded,” the story said.

Meanwhile, the Washington Post castigated Democrats for their “11th-hour attempt to exploit a dormant issue.” The Post acknowledged the truth — “It is safe to say that Bush did very light duty in his last two years in the Guard and that his superiors made it easy for him” — but waved it off as an irrelevance.

During Bush’s first term, the AWOL story continued to burble on the Internet, including on websites like The AWOL Project and awolbush.com, but things didn’t pick up again until his reelection campaign.

In January 2004, iconoclastic filmmaker Michael Moore called Bush a “deserter.” And, as Moore himself wrote: “The pundits immediately went berserk. … As well they should. Because they know that they — and much of the mainstream media — ignored this Bush AWOL story when it was first revealed by an investigation in the Boston Globe (in 2000).”

Factcheck.org, even then the toothless watchdog of the Washington cocktail-party crowd, channeled the elite media with a response headlined: “Bush A Military ‘Deserter?’ [sic] Calm Down, Michael.”

In February, then-Democratic National Committee chairman Terence R. McAuliffe called Bush “AWOL,” and created a brief flurry of coverage. The Globe’s Robinson used the news peg to review the evidence he had collected four years earlier.

In response, the then-White House press secretary Scott McClellan issued robotic non-denial denials — “The President fulfilled his duties. The President was honorably discharged” and “It is really shameful that this was brought up four years ago, and it’s shameful that some are trying to bring it up again.” The White House released 400 pages of records, none of which were definitive. But the elite press, looking for a smoking gun in a case where the real clue was more of the dog-that-didn’t-bark-in-the-night variety, lost interest again.

The story wouldn’t entirely die, however. It came back with a vengeance in September, two months before the 2004 election.

On September 5, the Associated Press, which had sued in a failed attempt to see a microfilm copy of Bush’s entire Texas Air National Guard personnel record, declared: “Documents that should have been written to explain gaps in President Bush’s Texas Air National Guard service are missing from the military records released about his service in 1972 and 1973, according to regulations and outside experts.”

On the morning of September 8, the Boston Globe published Walter Robinson’s full-fledged reexamination of documents old and new, concluding that “Bush fell well short of meeting his military obligation.”

That same day — just hours before CBS aired Rather’s specious report — U.S. News published another thorough debunking of the Bush apologists, describing how “new examination of payroll records and other documents released by the White House earlier this year appear to confirm critics’ assertions that President George W. Bush failed to fulfill his duty to the Air National Guard during the Vietnam War.”

So Dan Rather, who aired his report that night, was hardly the first to report the story. He was simply the last.

Truth is a really odd movie. The casting alone makes it clear that the filmmakers consider Rather and Mapes to be heroic, sympathetic figures. But because the artless screenplay sticks mostly to the truth, most viewers will not be inclined to see things that way. Its painfully cliched establishing shots will give them plenty of time to mull this contradiction. Avoid it. Instead go see Spotlight — a film opening in November about another investigation by Walter Robinson and the Boston Globe team — where the journalistic heroes actually do something heroic, and it’s great to watch. (Disclosure: Spotlight was partially funded by The Intercept’s parent company, First Look Media.)

The best that can be said for Rather and Mapes is that they didn’t intend to screw up the truth. But they did.