"but trained at Aberdeen Proving Ground "
yes, in my Officer Basic Course at good-old APG I was a Reserve commissioned officer on active duty
in my class were some National Guard officers from their States completing the course which would be required for promotion
there MIGHT have even been some Regular Army Officers, commissioned out of West Point - but I don't remember any for sure
Most officers then came from ROTC with a Reserve Commission
That was what I remembered, but since I wasn't the guest of honor I couldn't say for sure.
(Even though I was the one who had to rip all the old unit insignia off his ODs and sew the new ones on . . . :-D )
When were you at APG? Husband was there fall of 1973, then joined a USAR Chemical Corps unit in Camp Kilmer NJ.