These days the armed forces are allocated so many other roles - peacekeeping, search and rescue, disaster relief - that it's easy to overlook this. Notwithstanding the apparent desire of successive governments to transform our military into a sort of uniformed branch of Volunteer Service Abroad, Harry has reminded us that its core function is fighting.
Of course the enemy sees their job in a similar light, hence the saying "kill or be killed" or, as Harry put it, "take a life to save a life".
Judging by the reaction to the deaths of five of our soldiers in Afghanistan last August, some Kiwis appear to believe that being killed while on active service in a war zone is like being flattened by a runaway hay bale while going for a walk in the countryside: a desperately unfortunate freak occurrence.
The other widely expressed view was that our soldiers shouldn't have died because they shouldn't have been in Afghanistan in the first place. That raises the question of what would constitute a just war, a cause worth sacrificing lives for. There are those who give the impression that they would object to lives being put on the line for anything short of resisting an invasion by P-crazed cannibals from outer space.
This mindset reduces the armed forces to a purely ornamental function.
It has to be said that Harry's reference to video games included an unfortunate choice of words: "It's a joy for me because I'm one of those people who loves playing PlayStation and Xbox, so with my thumbs I like to think that I'm probably quite useful."
Well, quite, your highness, although perhaps "joy" is ever so slightly unseemly in this context.
But again, in his gauche way, Harry has put his thumb on it: the further removed from the death scene the killer is, the more warfare becomes virtual combat.
Ever since the invention of the catapult mankind has been able to kill from a distance, but technology has taken lethal detachment to a whole new level.
The person who presses a button in order to kill someone over the horizon is a bit like the bureaucrat in an authoritarian regime's security apparatus consigning "anti-social elements" to prison camps or torture chambers or firing squads with a stroke of the pen. It's easy to cause suffering at several removes; you don't have to look your victims in the eye or hear them scream. Twentieth century history suggests it can in fact be addictive.
There's mounting criticism of the latest manifestation of virtual war, the unmanned drone. Understandably so, since it sometimes seems as if the targeting policy is "near enough is good enough" and scant effort goes into ensuring that the intended target is alone and not surrounded by wives and children, when the drone strikes.
But if groups choose to declare war to the death on an entire culture and set out to kill civilians in large numbers by any means, including converting civil airliners into guided missiles, they shouldn't be surprised if their foe fights back with just as much resourcefulness and ruthlessness.
And when all is said and done, drone strikes cause far less collateral damage than sustained bombing campaigns or counter-insurgency wars waged by an army of occupation.
In a curious way and perhaps without really intending to do so, Harry's adoption of the front line soldier's self-protective, mock-callous nonchalance is both an assertion of relevance and a declaration of independence from an establishment that uses the military as a prop in the royal fairytale.
It seems their warrior prince prefers the battlefield to the gilded cage.
