He did not start this war. He cannot stop it. Yet Afghanistan is fast becoming the third crisis to face the prime minister - as if the economic and political crises were not enough.
It is, above all, a crisis of confidence. Few fear defeat, but there are growing doubts among public and politicians alike about whether "success" can be achieved - whatever success actually means.
Ironically, those doubts are being fed, not by those contemplating withdrawal, but by many in the military who lack confidence in their political master. It is their cause which has been taken up so stridently by the Sun.
It was this which was underlying the prime minister's emotional clash this week with Jacqui Janes - the mother of the 20-year-old guardsman who died in Afghanistan.
She argued with him not about the need to bring the boys home - she backs the war - and not primarily about his handwriting, but about the lack of resource being committed to the fight.
When Gordon Brown called her, she told him "Many, many years ago, in 18-something, somebody said the biggest enemy of our army was our Treasury... They were so right."
Janes, whose sons she called "fifth generation infantry", was reflecting a view held by many in the military who have not trusted Gordon Brown since he was chancellor.
Early in his days at Number 11, Brown clashed with the then chief of the defence Sir Charles Guthrie about the defence budget. "You don't think I understand defence, do you?" a defensive Brown said to Guthrie. The General's reply was forthright "No, I bloody well don't."
It is a view shared by many ex-service chiefs who regularly line up in the House of Lords to criticise the prime minister. Field Marshal Lord Inge has declared that the armed forces never really believed Brown was "on their side".
Guthrie has accused the prime minister of "dithering" over troop deployments to Afghanistan. Though Gordon Brown strenuously denies turning down a request for 2,000 more troops in February, it's clear that he did turn down a request for a major new deployment of 1,500 troops.
Now - months later - when those extra troops have been committed, the former generals grumble about what they see as political and not military conditions attached to their deployment.
If they are needed to do their job, they ask, why should it matter whether other Nato countries do more or President Karzai tackles corruption or increases the size of the Afghan army?
Those conditions were laid down to meet the pressure coming from the public and politicians, including some in the cabinet who have been studying accounts of how the American military sucked politicians into ever-deeper involvement in Vietnam.
Friends of the prime minister reply that while some of the earlier criticisms were fair, they are now out of date and are being used by his political opponents. Guthrie and Dannatt are, they say, both Tory advisers. The Sun is now an openly Tory newspaper.
They concede that Brown once paid little attention to defence - a book of his speeches published during his bid to be PM contains not a single speech on the subject in its more than 400 pages of nine years' worth of speeches.
However, they say, he became actively engaged during the summer and gathered around him a war cabinet which met once a week and now meets once a fortnight.
What's more, they point out, it is in America that the big decisions about Afghanistan will be taken.
President Obama has spent weeks making up his mind or, it would appear, not making up his mind about what to do next. His military, diplomatic and political advisers are publicly split on the issue.
Those friends of the prime minister note bitterly that the president has been praised for taking his time, considering all the options and resisting the military's demands whereas Gordon Brown is now paying a heavy political price for allegedly failing to give the leadership this war demands.