I'm looking for advice on additional avenues to research my grandfather's WW1 military service.
My grandfather was born in 1899 in Hlivistia (present day Slovakia) and lived in this village (just north of Sobrance, Slovakia) until he was called up for service. This area was the recruiting area for IR66.
From other sites/comments, I'm told class 1899 and 1900 (birth years) were both called up in 1917. The person supplying the information was not able to provide the month. Depending on month, my grandfather would have been 17 or 18 years old.
There are no surviving records in Hlivistia or Sobrance (lost in a fire in the 1970s).
Hungarian military archives replied to my enquiry that records for classes 1850-1899 were lost/destroyed during the second world war.
This area once fell in Zemplin county. I'm not sure if the is still a regional/county government that may house records?
Per some earlier replies to another thread, IR66 served on the eastern front (Russo-Romanian) in 1917/18 with II./IR66 briefly attached to a mountain Brigade on the Isonzo front.
My grandfather would have been a low-ranking foot soldier/draftee. From what I gleaned from Brian, the only notable thing about IR66 (If he served in this regiment) was that it was more multinational than most-- Magyars, Ruthenians, and Slovaks. The training depot for this Regiment was in nearby Ungvar (present day Uhzhorod, Ukraine)
Given that I have no documentation of any kind to verify my grandfathers service, can anyone suggest other research avenues for finding information? I've run out of ideas.