Thanks, you're right. There were rebreathers but not scuba. Olexa was trained to swim as an army Sea Scout. Program was dropped and he never was deployed as such.
Embattled Witness by Bernard Haring. Catholic priest goes to war (drafted and served as saniter/medic).
From what I've read, these were free divers led by Draper Kauffman. Their primary job was as demolition experts (UDT). Interesting read so far.
I recently read Swan or Slog, a really good book about the British army during Op Veritable. Even after 80 years, the author showed that there are myths which need to be dispelled.