[Ger-Poland-Volhynia] Polish army?

[Sharon Kitter]

I also have a question along this area.. My dad was told by his father 
(who was born in Russia/Poland.. ) that he had been in the Polish army. 
This would have been around 1916. He would have been 14 years old. This 
sounded very odd to me, as Poland wasn't a country at the time and he 
was, I thought, very young.

Does anyone have any insight on that?

Thanks,
Sharon Kitter