Just to put this in context.....
Someone asked for study of whether or not including transgenders (or was it women, or homosexuals?) in an army would cause problems. Archie asked if we needed a study of straight white male armies.
I noted that such a "study" had already occurred, referring to the beaches of Normandy, but it could have been Gettysburg, or Waterloo, or Hastings, or Cannae, or Kadesh, or any of a zillion battles of history. However, I happened to have chosed a D-Day reference, and Archie was pointing out that the losing side was even straighter and whiter than the winning side that day.
It's a fair point, but it also misses the point, which is that we don't need a scientific study to determine how things will work if we do things the way we've always done them. We can study history for examples of including gays in the armed forces, or making up an army of multiple ethnicities. However, we can't do that with women, and we can't do that with transgenders. We can't do it with women because no army prior to modern times has ever done it, and we can't do it with transgeders because until recently no one had a concept of "transgender".
What I was making fun of with my comments, though, was the idea that we would need some sort of study of women's performance in the armed forces until recently, when modern machines made it possible to engage effectively in warfare if you lacked physical strength. Had women taken the field at the Battle of Hastings, they would have been hacked into little bits, and it is absurd to think there would have been any other outcome.
All right, but what does that have to do with transgenders. Well, declaring yourself to be a male, or even rearranging some skin between your legs, won't change the number of pushups you can do. Also, whether or not everyone likes to admit it, there is a social aspect of military service and even of participating in combat, and people act differently toward men and women, and transgenders are.....one of the above.
So, it's worth asking whether it seems like it would be a good idea to do things differently, because there is more at stake than someone's feelings.