Three hours and 19 minutes.

That’s how long it took from the first, desperate pleas for help from the Capitol Police to the Trump Pentagon on Jan. 6 until the D.C. National Guard finally received permission to help put down the bloody insurrection.

During those 199 minutes, the mob sacked the Capitol. People died. Overwhelmed Capitol and D.C. police were beaten. Lawmakers’ lives were jeopardized. And violent extremists defiled the seat of government, temporarily halting the certification of Joe Biden’s victory.

“At 1:49 p.m., I received a frantic call from then-chief of United States Capitol Police, Steven Sund, where he informed me that the security perimeter of the United States Capitol had been breached by hostile rioters,” Maj. Gen. William J. Walker, commander of the D.C. Guard, testified Wednesday to a joint Senate committee investigating the attack on the Capitol. “Chief Sund, his voice cracking with emotion, indicated that there was a dire emergency at the Capitol, and he requested the immediate assistance of as many available national guardsmen that I could muster.”

Walker immediately alerted senior Army leadership — and then waited. And waited. Approval to mobilize the guard wouldn’t be received until 5:08 p.m.

At best, this was a catastrophic failure of government. At worst, political appointees and Trump loyalists at the Defense Department deliberately prevented the National Guard from defending the Capitol against a seditious mob.

The man ultimately responsible for the delay, Christopher Miller, had been a White House aide before Donald Trump installed him as acting defense secretary in November, as the president began his attempt to overturn his election defeat. Miller did Trump’s political bidding at another point during his 10-week tenure, forcing the National Security Agency to install a Republican political operative as chief counsel.

Also involved in the Pentagon delay was Lt. Gen. Charles Flynn, brother of disgraced former Trump adviser Michael Flynn, convicted (and pardoned) for lying to the FBI. Michael Flynn had suggested Trump declare martial law, and he helped to rile Trump supporters in Washington the day before the Capitol attack. The Pentagon had falsely denied to Post journalists that Charles Flynn was involved in the pivotal call on Jan. 6.

Representing the Pentagon on Wednesday fell to Robert Salesses, who haplessly tried to explain the delay. An hour and six minutes of the holdup was because then-Army Secretary Ryan McCarthy “was asking a lot of questions” about the mission. Another piece of the delay: The 36 minutes between when the Pentagon claims Miller authorized the action and when the D.C. Guard was informed of the decision. “That’s an issue,” Salesses allowed.

Curiously, the Pentagon claims Miller’s authorization came at 4:32 — 15 minutes after Trump told his “very special” insurrectionists to “go home in peace.” Was Miller waiting for Trump’s blessing before defending the Capitol?

The Pentagon’s 199-minute delay looks worse in light of a Jan. 4 memo Miller issued saying that without his “personal authorization” the D.C. Guard couldn’t “be issued weapons, ammunition, bayonets, batons or ballistic protection equipment such as helmets and body armor.”

The Army secretary added more restrictions the next day, saying in a memo that he would “withhold authority” for the D.C. Guard to deploy a “quick reaction force” and that he would “require a concept of operation” before allowing a quick reaction force to react. McCarthy even blocked the D.C. Guard in advance from redeploying to the Capitol guardsmen assigned to help the D.C. police elsewhere in Washington.

Without such restrictions, Walker, the D.C. Guard commander, could have dispatched nearly 200 guardsmen soon after the Capitol Police mayday call. “That number could have made a difference,” Walker testified.

Sen. Rob Portman, an Ohio Republican, was incredulous. “There are three unarmed national guardsmen who are helping with traffic control … and they were not permitted to move a block away without getting permission from the secretary of the Army?”

“That’s correct,” Walker replied.

Miller “required the personal approval of the secretary of defense for the National Guard to be issued riot gear?” Portman asked.

“That’s correct,” Walker replied. “Normally for a safety and force-protection matter, a commander would be able to authorize his guardsmen to protect themselves.”

But this was not normal. The Pentagon claims the restrictions were in response to criticism of the heavy-handed deployment of the National Guard in Washington during racial justice protests last summer. Maybe so. But Walker testified that when the police chiefs “passionately pleaded” for the Guard’s help on Jan. 6, senior Army officials on the call said it wouldn’t be “a good optic.” They thought “it could incite the crowd” and advised against it.

During this moment of crisis — an attempted coup in the Capitol — the defense secretary and the Army secretary were “not available,” Walker testified.

The nation deserves to know why.