The usual claim that Modernity represents an extraordinary degree of change and dynamic uncertainty must butt its head against the co-current rise of hyper-rigid nationalism in the same time and space.
This newly reified term, nationalism, was generally based upon a single ethnicity, which was usually coded at the time, incorrectly, as "race".
No longer were all citizens of France or Germany regarded as French or German by simple reason of being legal citizens.
Instead a hopelessly il-defined and yet paradoxically rigid innate quality made you either part of The Glorious French Race or not.
Not, meant you belonged to another nationality slash ethnicity cum race.
You had no choice to say that you shared a number of different groupings varying upon your politics, religion, main language , place of birth and parentage.
Individuals effectively ceased to be individual and had to be members of , and hyper-loyal to , a particular block of humanity, the Italians or French, etc.
Contrast this to the Middle Ages's Christians who saw the Jews not as a solid group to be put to the sword, but as a group of individuals - some sinners and some saved - depending upon whether or not they individually accepted Christ and were baptized.
So WWI's vestiges of chivalry and empathy and altruism were not crowded out by old fashioned and immoral individual selfishness ( which was not any more common or any more popular than it has always been).
No, they were replaced by a new supposedly highly moral form of group selfishness.
People protested that concern for your kin had always been ruled morally legitimate - all that had changed, under Modernity, was that there were a lot more kin in your vastly enlarged German/British/Russian family.
By contrast, a pretty Russian or a handsome German was no longer a possible marriage mate for a French youth , as an attractive fellow human being who just happened to - currently - speak different and go to a different church.
Now different ethnicities might as well been different species and marriage with other ethnicities seem dangerously close to bestiality.
Not only were you rigidly placed in one ethnicity - from birth and fixed rigidly for all time - but your entire ethnic group was also rigidly and permanently set in a hierarchy of worthiness, from valued to useless.
So, regardless of the actions of individual Italians, individual combat units or individuals battles, Italians as a group were dismissed ,in advance, as permanently bad soldiers.
In this bizarre moral universe of Modernity,two billion human beings around the world saw the big nations beat up the little nations and did nothing, but each rushed loyally into fearsome combat the moment their own nation was itself attacked.
Each warrior felt he or she was on some moral high road but they were not.
For if Hitler hadn't attacked Russia and declared war on America, Europe would probably still be under his descendants' heel.
Altruism was at a very low ebb between 1931 and 1946 and so all the more reason to honour it where ever and when ever it was found...