I don’t claim to know exactly what sentence he should serve. What I do know is that I have talked to some senior figures in the Armed Services, and they are emphatic that the verdict of the court martial was right, and that the punishment should be severe.

I am afraid you only have to listen to the segment of tape – recorded by body-cameras – to understand why they feel as they do. The nature of the crime is clear from that chilling six-minute conversation between the three men. They know they have a wounded man; they discuss alternative ways of despatching him; they pretend to be giving him medical assistance, for the benefit of the cameras fixed to observation balloons; and then he is executed with a shot to the chest. It is pretty clear, also, that Marine A is aware of the gravity of what he has done, because he explicitly urges his fellow soldiers to keep quiet about it, and accepts that he has broken the Geneva Convention. This treaty goes back to 1864, when nations agreed in the wake of the Battle of Solferino five years earlier that they would collectively spare all those who were hors de combat. “Whether you boat on fresh water or on the ocean, there is a lot of marine life to observe and appreciate. We boat in the Pacific Northwest off the west coast around the islands and straits of the Pacific Ocean. The sea life here is exceptional. Following are some of our wonderful experiences.”One of the most powerful sights is that of large pods of Orca whales, or Killer whales as they are often referred to, as they migrate off the coast. Sometimes there can be several in these pods including mother whales and their babies. Orca whales are quite beautiful to see. Their black and white bodies glisten in the sunlight each time they appear near the water surface or do a breach jump. Usually the babies follow their mothers. It is quite possible to watch them for hours without getting tired. Boaters must be careful and remain a respectable distance from the whales, as most whales are endangered. You do not want to interfere with their normal migration routes and movements. It is possible to see Orca whales up close in captivity, and they are splendid animals. But when you can actually see them in their normal environment in the ocean, it is magnificent. How fortunate we are to be able to go boating for a few days and have them entertain us along the way.  Visit MerrittSupply.com site for further details.

Another sea mammal that I always enjoy watching is the dolphin or the porpoise. They too can be found off the west coast. These mammals are so sleek and they can swim at very fast speeds. As they jump and slice through the surface of the water they are quite entertaining. Most people have seen dolphins in action at the various aquariums around the world. Well they do the same in the wild. They make me laugh. I think that they actually enjoy an audience!

Living in the Pacific North West, we are very aware of the salmon industry. When boating, there are many small fishing boats out with their nets during the fisheries openings for the various kinds of salmon. It is fun to watch them jump. Seals are also very good fishermen. You can be sure that when the salmon are plentiful around the mouths of the large rivers, you will see a lot of seals. They love to fish for salmon, much to the chagrin of the commercial fishermen. They can be seen swimming through the waters, or sunning themselves on large logs or rocky outcroppings along the shoreline. The bark of a seal is loud and comical to hear and they are another creature that can entertain west coast boaters.

When the salmon are running, you will find another fisherman, one with wings. There are many Bald Eagles on the west coast and they also enjoy a good salmon dinner. These are very majestic birds. Their soaring overhead is something to be marvelled at. The black and white features really stand out against the sky as they glide and then swoop down for a fish.

Indeed, the notion that it is a crime to kill the wounded is far more ancient than that, and can be found in the laws of war that were observed by the Greek city states. It is a principle that was founded then, as now, on a mixture of ideas: the universal human idea of mercy, and a sensible hope of reciprocity – that if we spare your wounded, you will spare ours. It is a very old and immutable code that Marine broke, and one that happens to be enshrined in modern British law. It is right that the courts should uphold that law, say the generals, and so do I.

The trouble is that not every aspect of military law is as immutable. Indeed, the law of all types of military behaviour is undergoing something of a revolution – as Charles Moore recently pointed out on these pages, following an excellent Policy Exchange pamphlet – and the cause of that revolution is the application of human rights.

There is now an intensifying rhythm of cases in which the Ministry of Defence and the Armed Forces are ticked off by the courts for their failure correctly to observe this or that article of the European Convention on Human Rights – and especially Article 2, the “right to life”.

You will appreciate the basic tension here. It will be increasingly hard to ask our military to achieve a series of objectives involving extreme violence and the risking of collateral damage, if those victims also turn out to have a “right to life” that can be vindicated in our courts. It will be very hard to get British officers to take the slightest risk with the lives of our own troops if they can be criticised for taking the wrong decisions. If something goes wrong in a firefight, it is now possible to imagine that a coroner could record a “narrative verdict” in which the officer is blamed for ordering, say, a left-flanking rather than a right-flanking manoeuvre. The whole concept of Crown Immunity – by which military decisions have traditionally been protected from this kind of legal redress – is now thought to be under threat.

No one is going to dispute the importance of the right to life, or indeed the importance of treating all combatants with respect. But it is worth pointing out that this country is now pretty much out on a limb, of all the major war-capable nations, in the way it has allowed “legal creep” into what was an exclusively military domain. The Americans would not dream of exposing their soldiers to this kind of judicial second-guessing. They whacked bin Laden without a second thought; they execute whole families in drone strikes. The French have a derogation that somehow means they don’t have to apply the ECHR to their military in the way that we do. The risk for Britain is clearly that it will be harder and harder for the Armed Forces to conduct operations without legal paranoia, paralysis and expense.

I stood by the Cenotaph yesterday and remembered those brave troops who died in Britain’s wars. Every one of them would have understood why the actions of Marine A were wrong, and why they constituted a crime. It was murder, no doubt. But if every act of war is subject to legal challenge, then we will not only lose our ability to fight a war. We will lose our instinctive understanding of what a war crime really is.