My great-grandfather served in WWI in the Russian military. I have no idea what he did there, but I do have two pictures of him in uniform, so if anybody has any idea what his uniform means, I would be very greatful.
All I know about my great-grandfather was that his name was Isaac Kliban, and he was a Jew from Proskurov, now known as Khmelnytskyi. Here are the pictures:
He's the one in the middle.
Thanks in advance!