BBC World Affairs Editor John Simpson, who knows both Gen Stanley McChrystal and the man who will take over his duties, Gen David Petraeus, looks at what Gen McChrystal's sacking reveals about the Obama administration.
US President Barack Obama is lucky to have a general as good as David Petraeus to put into the job vacated by Stanley McChrystal. It means there should be no great problem keeping US policy in Afghanistan on track.
The trouble is that policy was starting to be questioned even before Gen McChrystal's mild indiscretion brought his career to an abrupt end.
And the manner of President Obama's reaction to a few remarks quoted in Rolling Stone magazine is already being interpreted as showing the president's weakness, rather than his strength.
A stronger, more self-confident president would have given Gen McChrystal a public roasting, then told him in as many words to get on with the job and keep his mouth shut in future.
Even though Gen Petraeus is a remarkably safe pair of hands, Gen McChrystal will be sadly missed in Afghanistan.
The government of Afghan President Hamid Karzai will miss him, because he understood the importance of winning the support of the Afghan people in fighting the Taliban - who, he said in an interview with the BBC some months ago, do not like the Taliban or want to have them back in power.
"It's not a popular movement, and so what we need to do is correct some of the ways we operated in the past," he went on. In particular, he has done everything he could to prevent the troops under his command from killing Afghan civilians.
His allies, particularly the British, will miss him too. Gen McChrystal is an anglophile with a Special Forces background. That tends to bring with it a closeness with and respect for the British special forces.
He was a particular favourite with the SAS, and not long ago was the guest of honour at a big dinner at their headquarters in Hereford.
Of course, it was unwise of him and his press advisers, who were experienced and able, to forget over a period of a fortnight that they had a journalist in their midst.
But the general's transgressions were pretty mild. Only a government as nervous as President Obama's about seeming weak and indecisive would have reacted so fiercely.
The problem is that the reasons for Gen McChrystal's irritation with Washington have not gone away.
There is a clear lack of decision about the way the war should be fought, and about whether and how there should be negotiations with the Taliban.
On Monday, this indecision cost the job of the most senior British diplomat in charge of Afghanistan, Sir Sherard Cowper-Coles. He is now on "extended leave" for disagreeing with the latest views in Washington about how to deal with the Taliban.
The politicians and soldiers involved in directing US policy are fighting among themselves, and the battle can be vicious.
Gen McChrystal, one of the ablest commanders America has produced during the last few decades, has fallen victim to this in-fighting as much as to his own bluntness and lack of diplomacy.
He wanted a much more clear-cut approach, free from the lack of decision and the squabbling that has caused such problems in Washington.
He suffered last year as President Obama put off a decision for month after month before agreeing to follow Gen McChrystal's (and Gen Petraeus's) advice about the way forward in Afghanistan. And he was too straightforward to keep his feelings entirely hidden.
Gen Petraeus, his superior officer and mentor who will now take on his job, will not make the same mistakes. Gen Petraeus has views which are no less clear-cut than Gen McChrystal's, but he knows how to dress them up diplomatically.
(He is, incidentally, no less of an anglophile and an admirer of the SAS than Gen McChrystal.)
As a man with an interest in the classics, Gen Petraeus has always followed the Latin injunction Fortiter in re, suaviter in modo (be tough in your aims, but smooth in the way you put them into practice).
Fighting a war with a nervous would-be micro-manager back in the White House and a swarm of potential critics will require all the toughness and smoothness at his disposal.
But we can be sure Gen Petraeus will be too canny to let his hair down within the earshot of any journalist.