Christopher Cradock is one of the most extreme examples of this, who knowingly sent his ships and men (many of them reservists and boy cadets) to their deaths against a vastly superior foe (numerically, technically and in crew preparedness/training) and did so without question since it was his job to do so. Understanding that kind of mind is difficult for us today.
Think you so? This question requires the examination of the term "acceptable casualties". This isn't something that most civilians ever think about so, when somebody from the "firing line" mentions it, they view him at best as callous but normally as utterly alien. So let's consider a few things....
You no doubt own a car drive it over roads and bridges for your personal benefit. How many people died or were seriously injured to make that possible? From the miners and oil field workers producing the raw materials of and needed by the car itself, through the factory workers building the car and the refinery workers making the fuel, not to mention the road- and bridge-builders. Then consider that highway accidents themselves are the leading cause of death amongst young adults (IOW, folks of prime miltary age, with all their lives ahead of them). And consider that, in the US alone, nearly as many people die in car crashes in 1 year, every year, as died in the Viet Nam War in 10 years.
But nobody thinks about that at all, so long as they've got a car, relatively affordable fuel to put in it, and roads to drive it on. IOW, all the peolpe who were killed or maimed to make it all possible, those killed and maimed enjoying the end product, and even the maiming of an individual dirver, are all "acceptable casualties". Why? Because despite all this bloodshed, nobody wants to give up their car, their roads, or their bridges, even with close family members die in wrecks or they themselves are maimed, and nobody cares about the mine collapses or cancer from a lifetime of working in a refinery. If anything, folks only complain about the monetary cost of cars and fuel, but never the human cost. They are perfectly willing to accept all the casualties along the way so long as they can keep on driving. How callous and alien is that?
Here's another everyday example: the fireman. A fireman is, on average, a net asset to society. While there are exceptions, the average fireman is full of the self-sacrificing virtues that most folks consider good, perhaps even heroic. He's willing to get paid diddly divided by squat to risk his life and health for the safety of his community. But despite this, society values the fireman less than the lowest bum on the street, who has never done an honest day's work in his life. Why? Because society expects the fireman die trying to save the bum when the bum's meth lab explodes. But that's an acceptable casualty exchange in society's eyes. Otherwise society wouldn't have created firemen.
Now consider a member of the armed forces. He grows up seeing all the above in his society yet is willing to get paid diddly divided by squat to go take a bullet on some foreign shore, so that it all can continue. Why? Because part of it belongs to him and if he can't change the big picture, he can at least keep his little part of it running on his standards.
So tell me truly, who is harder to understand?