You are right, blame it on bad wording. Some of us are better than others in physical endurance and stamina; that does not make them less martial. They get fewer opportunities in the military because recruiters select for endurance and stamina; when recruiters select for motor skills, the fallacies become apparent.
Martial qualities are not entirely defined by physical endurance and stamina. Consider the examples of continental Europe. The English have been known to be good soldiers throughout history. But at different periods, other nationalities have had their day. Most recently, it was the Germans. Before that, it was the French. Before them, the Spanish; they were unbeatable at a certain period of time. The Swiss, the Italians (as Romans) and the Greeks have all had their day. So physical endurance and stamina are not the only characteristics that make martial races.
Coming back to my botched wording, I do think that Bengalis lack physical endurance and stamina, compared to others: the Punjabi and the Haryanvi, for instance; that applies to Biharis also, vis a vis the Punjabi or the Haryanvi. The fallacy of physical endurance and stamina constituting martial characteristics was proven by the British in most recent times, when they conquered the Punjab with an Army largely drawn from the Biharis; they also beat the Marathas, and, on occasion, the Afghans. In short, while Bengalis and Biharis lack the physical stamina and endurance to be found in the north, they are not short of martial prowess, merely short of physical endurance and stamina. If these two had been critical, Napoleon would not have won many battles. Nor would the Romans, who had a torrid time against the Gauls before their superior military prowess led to the conquest of Gaul; they had an equally torrid time against the Germans, but never did get the upper hand.
The business of martial races was an artificial construct to justify recruiting from the loyal Sikhs and in course of time, PMs and RMs, leaving out the mutinous Biharis who had helped the British to conquer most of north India. This became a self-fulfilling prophecy; soldiers recruited from a region tended to encourage youngsters from that region to enrol, and that led to a steady deepening and broadening of the urge to join the military. Over time, there was no tradition of joining the military in parts of India, while there was a robust tradition in other parts. When you have 90% of your soldiers from certain districts, it is tempting to think of those districts as better recruitment areas.
My response above.
It is interesting that the origins and antecedents of officers in the Indian Army seems to be changing. Besides the traditional officer classes, drawn from the middle classes, there are now the sons of JCOs or simple soldiers, and there are those who select a military career over one in civilian life, those, that is, with options who selected the military life.
