Hmmm... I can only say that the .38 was found to be somewhat lacking in those days when the Army strayed away from the .45 colt.. A determined “Moro” warrior with a machete was apparently more than a match for the Army’s new .38cal. Hence the birth of the 1911 .45ACP.
But, with when your back is against the wall, a big stick is better than nothing... :)
That was not the .38 Special, which was fielded in 1902. It was the .38 Long Colt, a significantly weaker cartridge.
Another factor, seldom considered, is the Army also found the .30-40 Krag was lacking in "stopping power". The Moros were often drugged up, and it took a central nervous system hit to stop them.
The .38 Long Colt had a 150 grain bullet at 770 fps. The .38 Special standard load was 158 grain bullet at 855 fps.