The other shoe finally dropped on Patrick Shanahan, who had been announced as the nominee for Secretary of Defense but never formally submitted. He’s going to spend more time with his family, Donald Trump announced on Twitter. Usually that means a dismissal, but this time the cliché actually came closest to the truth:

There had been plenty of speculation that Shanahan had lost favor with Trump after Shanahan’s reaction to the USS John McCain incident. His absence from a trip this morning by Mike Pompeo to CENTCOM was noted by several reporters, including Adam Weinstein and Olivier Knox, for its strange breach of protocol. Shortly after Trump’s announcement, however, the Washington Post reported on what actually drove the decision. It was, in fact, a family matter — one that the FBI was investigating, USA Today reported:

The FBI has been examining a violent domestic dispute from nine years ago between acting Defense Secretary Patrick Shanahan and his then-wife as part of a background investigation ahead of his possible confirmation hearing to be President Trump’s permanent defense chief.

The incident, in which Shanahan and his then-wife, Kimberley, both claimed to the police that they had been punched by the other, did not surface when Trump nominated Shanahan to be the Pentagon’s second-in-command two years ago, or when he was selected to be the interim defense chief this year.

Shanahan said he “never laid a hand on” his former wife. His former wife, who now goes by the name Kimberley Jordinson, said she stands by her account.

How did this not come out earlier? Shanahan went through a relatively calm confirmation hearing for his current position as deputy Secretary of Defense. That requires an extensive FBI investigation. Being accused of domestic violence should have come to the committee’s attention at some point. If the FBI failed to notify the committee about these issues — we don’t know yet for sure that they did — that’s a big problem. The FBI background check is intended in part to make sure high-ranking government officials aren’t susceptible to extortion. This might not rise quite to that level, but it’s not a nothingburger either.

Let’s get back to the specifics in the domestic-violence allegations. Was Shanahan the aggressor? He says no, but his ex-wife says yes. The bigger political problem might be how he tried to excuse a separate incident between his wife and his son:

In November 2011, Shanahan rushed to defend his then 17-year-old son, William Shanahan, in the days after the teenager brutally beat his mother. The attack had left Shanahan’s ex-wife unconscious in a pool of blood, her skull fractured and with internal injuries that required surgery, according to court and police records.

Two weeks later, Shanahan sent his ex-wife’s brother a memo arguing that his son had acted in self-defense.

“Use of a baseball bat in self-defense will likely be viewed as an imbalance of force,” Shanahan wrote. “However, Will’s mother harassed him for nearly three hours before the incident.”

Shanahan talked with Post reports last night after being asked about it since January, according to the paper. He says that memo was written for private conversation and was never intended to be made public. That semi-justification for assault with a deadly weapon is particularly regrettable now, Shanahan says, but he was consumed with the need to protect his son:

As he later wrote in the divorce case, Shanahan said Monday that he does not believe there can be any justification for an assault with a baseball bat, but he went further in the interview, saying he now regrets writing the passage.

“Quite frankly it’s difficult to relive that moment and the passage was difficult for me to read. I was wrong to write those three sentences,” Shanahan said.

“I have never believed Will’s attack on his mother was an act of self-defense or justified. I don’t believe violence is appropriate ever, and certainly never any justification for attacking someone with a baseball bat.”

As late as last week, even with this sword of Damocles dangling over Shanahan’s head, he was actively fighting for his nomination. One has to wonder why, and why Shanahan decided to accept any appointment that might expose this. “You have to know how to hit a curveball,” Shanahan said about dealing with the Trump White House, but sometimes you have to know how to hold off on one, too.

For now, Trump will move Mark Esper up to run the Pentagon while he searches for another candidate. Perhaps Boeing will take Shanahan back, although they likely will be sensitive to any bad publicity their former exec carries now, especially while they deal with their own on the 737 Max scandal. This bizarre flameout comes at a particularly bad time, with tensions rising in the Gulf of Oman and with China and North Korea as well. Trump had better nominate someone quickly — and make sure he or she is unimpeachable this time around.