The toll of these losses and of repetitive combat deployments is far-reaching: military families are overstressed, and junior and midlevel officers are leaving the force in large numbers.

As a result, the army now promotes almost 100 percent of eligible captains to major and about 90 percent of majors to lieutenant colonel; less than 15 years ago, these figures were 25-30 percentage points lower.

If these trends continue, the army will soon have an entire generation of officers who for the first 20 years of their careers did not face the prospect of not being selected for a merit-based promotion.

That is U.S. Army Colonel Matthew Moten writing in Foreign Affairs. Full text here.

Of course there is quite a bit of self-selection into who sticks around in such a difficult job, but this could have both positive and negative effects on officer composition.