Soldiers' deaths will not guarantee Helmand success
Casualties are rarely an accurate measure of success in military operations.
The Duke of Wellington used to call it the "butcher's bill", recognising that the only thing worse than paying the price of victory was paying it for failure.
In the current British-led offensive in Helmand - Operation Panther's Claw - there are worrying signs that the loss of life in recent days may not produce the lasting success most people in Britain would hope for.
These indicators have little to do with the willingness of the British (and Danish) troops to suffer and bleed in carrying out their orders.
They are to do with concerns that the hard won gains of these house to house fights, in terms of clearing out pockets of Taliban resistance, will not be sustainable.
This is why Prime Minister Gordon Brown has been on the phone to President Hamid Karzai, urging him to send more Afghan security forces to the troubled province.
The US model of "clear, hold and build" envisages tough fighting.
I was an eyewitness to this in the bitterly contested Baghdad suburb on Doura in April 2007.
The platoon I was embedded with lost three of its 36 soldiers, and had a further 10 wounded. The figures for the battalion to which they belonged were 18 killed and 60 wounded.
The unit which followed them lost nobody - by then the success of the new US tactics and surge had made the neighbourhood dramatically less dangerous.
But the Iraqis were ready to step in rapidly behind the Americans in newly established Joint Security Stations. Now they run Doura and the US troops no longer patrol.
General David Petraeus, architect of those tactics, and now overall commander of US troops in the wider Middle East, predicted that this summer's fighting in Afghanistan would bring heavier casualties to Nato and indeed to local civilians.
But, like commanders through history, he expects the hard fighting to produce results.
The problem with Operation Panther's Claw is this. There are 3,500 British and 500 or so Danish troops involved. There are about 250 members of the Afghan National Army (ANA).
Another two companies of ANA soldiers are supposed to arrive in August and a few hundred police too.
Even being charitable, it is unlikely that the Afghan security forces will top 1,000 in an area where the population is believed to be between eighty thousand to one hundred thousand.
There will not be enough Afghan troops to sustain security, unless of course, the Taliban give up the game entirely in the area.
Nato's options in this will be - to pressure the Afghan government into sending more, to take much of the strain locally with Nato troops, or to accept that some of the gains of recent fighting will be lost.
We are already witnessing the pressure on Mr Karzai to send more.
But if foreign troops end up sustaining a lasting presence in the area they will be "fixed", and unable to operate elsewhere.
Senior British officers are very reluctant to accept that they will clear areas they cannot hold in the long term, and even suggest that Operation Panther's Claw will stop if the Afghans do not provide sufficient forces to safeguard the gains.
But in truth the British brigade commander leading this operation will probably have to decide how far to push his advance long before he really knows how many Afghan forces will eventually turn up.
Even when they come, the police in particular are likely to be of dubious quality.
Then add another grim cloud on the horizon - that the British Army's local partners in two summers of heavy fighting in the province, the ANA 3rd Brigade of the 205th Corps, will soon come to the end of a three year enlistment period.
A large proportion of them are expected to take their opportunity to quit the grimmest part of the country.
The answer to these problems lies in growing larger, more professional, Afghan forces.
This is an explicit part of the new US strategy, which has set itself the ambitious total of more than doubling the ANA's size in less than two years.
But pressing problems, like securing this August's Afghan elections, keep intervening before the ANA is really ready.
Nato - and even the Americans with mid-term elections looming in November 2010 - does not feel it has time on its side.
On an admin note, I'm sorry to have broken off the blog after embarking on my leave. This one will probably be my solitary entry before my return to Newsnight duties in late August. In the meantime I'll be doing the usual family summer holiday thing, but also continuing with some unpaid leave, which I am devoting to a research project.