He actually did it. On Wednesday afternoon, only an hour or so after completing the press conference equivalent of Buffalo Bill's Wild West, President Trump announced on Twitter that he has forced Attorney General Jeff Sessions to resign. He also named Sessions' replacement, the attorney general's own chief of staff, Matthew Whitaker. Whitaker's views about the limits of Special Counsel Robert Mueller's authority were instantly available, courtesy of CNN and Twitter. There is every reason to believe that Whitaker, to whom Rod Rosenstein is also surrendering oversight of Mueller's investigation of collusion between Trump and Russia, will do the president's bidding in ways that Sessions would not.

Sessions' departure means not only the likely end of the Mueller investigation but, despite recent remarks to the contrary from the likely incoming House Speaker Nancy Pelosi, the beginning of a process that may well lead to Trump's impeachment.

If Democrats do pursue impeachment, it will be close in the House — four defectors from a 222-person majority would bring them short of the necessary 218. But the appetite for impeachment among the Democratic caucus will be strong and Pelosi is not going to risk an uprising that would take away her speaker's gavel. She will let them have their way.

Whatever the outcome, the whole thing will be ultimately fruitless. Republicans have increased their majority in the Senate to at least 53. Removing the president from office following a successful impeachment in the House would require the cooperation of all 46 Democrats plus 14 members of his own party. Trump endorsed every single freshman GOP senator. Republican incumbents who won in close races owe him their re-elections. They are not about to fold. Meanwhile, two of his most reliable Republican critics in the Senate, Bob Corker of Tennessee and Jeff Flake of Arizona, have just retired. Another, the late John McCain, is deceased. He can expect a united front from Mitch McConnell.

The only chance Mueller has now is to produce any indictments he has prepared immediately. If any of them name Trump, they will gather dust until he is removed from office after 2020, or, more likely, I think, 2024.

Why has Trump forced this moment to a crisis by firing Sessions? Only an hour before the announcement he told members of the press that he was allowing Mueller's probe — which he dismissed as a "hoax" — to continue. When was Sessions' undated resignation letter prepared? Why bring the United States to the verge of constitutional implosion when there were good reasons to think that whatever its eventual conclusions, the investigation would stop short of actually accusing him of crimes?

Because he loves doing things like this. Wallowing in his self-described victory, attacking his enemies in the media before a national television audience, waxing romantically about the possibility of working with Democrats on infrastructure so long as they are on their best behavior: These were not enough. Trump is impulsive. He recognizes that one way or another this will mean the end of the cloud that has hung over his administration for two years. The gathering storm is over. Now comes the rain. Everyone's windows will be open to watch what happens next.

Fourteen or so hours after many of us went to sleep after watching the election results come in, the 2018 midterms feel like events from late antiquity. Only one man could have done this. Trump embodies the office of the presidency more fully than any chief executive in living memory. He has captured the imagination of a nation. He has subsumed its political and social life into his his private person. He is probably, by some kind of quasi-objective measure, the most powerful person who has ever lived. He is also a guy who says things like, "My fingers are long and beautiful, as, it has been well been documented, are various other parts of my body."

Let the impeachment proceedings begin.