Unbelievable. All he had to do was go to a US consulate and register your birth. I really do have a hard time believing they made you go thru a naturalization process. It was totally unnecessary under the law then and now. The Army gave you bad advice.
Our births were registered with the US consulates. My birth certificate is 4 pages long. But because we were born in foreign countries we could claim citizenship of those countries. At the time, the US didn’t recognize dual citizenship. This process was to prevent any confusion.