We know from history the powerful value of conducting an exhaustive probe of the Capitol attack

Six weeks have passed since domestic terrorists — egged-on by Donald Trump in the waning days of his presidency — led a deadly assault on the U.S. Capitol, yet nobody really has a full picture of the events of the day, nor of who should be held responsible.

That’s why U.S. House Speaker Nancy Pelosi is making the right call in pushing for a 9/11-type independent commission to investigate the Jan. 6 attack.

The commission will “investigate and report on the facts and causes relating to the Jan. 6, 2021, domestic terrorist attack upon the United States Capitol Complex . . . and relating to the interference with the peaceful transfer of power,” Pelosi said in a letter to her fellow Democratic lawmakers.

If allowed the time and latitude to properly do its job, the commission’s work could provide the public with a report detailing what happened that day, while making meaningful recommendations aimed at ensuring it doesn’t happen again.

And we know from history that there’s a lasting value in conducting these types of postmortems following a crisis. We did such reviews in Chicago after the 1919 race riots, nationally after the civil unrest of the late 1960s and, of course, after the 9/11 attacks.

As a society, we didn’t always heed the reports’ recommendations, but the historic record has been all the better because of them.

‘Find out how it happened’

The violent and frightening raid on the country’s citadel of government happened in broad daylight — not to mention on live television and social media — and yet there are scores of details about the attack that we don’t know, particularly about the security failures that occurred.

“There’s still more evidence that the American people need and deserve to hear and a 9/11 commission is a way to make sure that we secure the Capitol going forward,” Sen. Chris Coons [D-Delaware] said. “And that we lay bare the record of just how responsible and how abjectly violating of his constitutional oath President Trump really was.”

Even Trump toady Sen. Lindsey Graham [R-South Carolina] backs a 9/11 commission “to find out what happened and make sure it never happens again,” he told Fox News Sunday.

As was the case with the body formed after the Sept. 11, 2001, terrorist attacks, the Jan. 6 commission would have to be created under a law passed by the House and Senate and signed by the president. Government officials and lawmakers would be barred from serving.

And the 9/11 commission — formally called the National Commission on Terrorist Attacks Upon the United States — shows the panel’s work can be exhaustive. Formed in 2002, the 11-member commission and its investigators interviewed more than 1,200 people and examined 2.5 million pages of documents. Former Illinois Gov. James R. Thompson was a commission member.

Their 567-page report issued at the close of the probe two years later found the attacks could have been prevented if not for failures at the FBI and CIA. The report also detailed what happened on Sept. 11 and shed light on the rise of al-Qaida and Osama Bin Ladin.

9/11 commission co-chair Thomas Kean told PBS NewsHour he supports a similar panel to probe the Capitol attack.

“How did this mob get created? How was it — I mean, we don’t know still whether they planned it all ahead of time or whether some were incited on the spot. We don’t know that yet,” he said. “Find out how it happened, and find out the facts that everybody agrees on. Once you find out the facts, you can make the recommendations to ensure it never, ever, ever can happen again. But you have to have the facts first in order to make those kind of recommendations.”

What the public needs

The ultimate success of the commission, of course, would depend on how well lawmakers and the public heed its final recommendations. In 1968, the federal Kerner Commission — chaired by Illinois Gov. Otto Kerner Jr. — warned the country to solve racial discrimination in the wake of the civil unrest of the late 1960s.

“Discrimination and segregation have long permeated much of American life; they now threaten the future of every American,” the report found. The same words could be written today.

Will the country act on the recommendations from the Jan. 6 commission? We can cross that bridge when we get to it. Right now, the commission is just what the public needs.

Send letters to letters@suntimes.com.