It could have been messed up by the enumerator in 1930 when the Census was being taken. The easiest way is to do a military search right here. More info you provide. The more you might get back. He might have served only one year. We were not in the mix very long.
You should also check with NARA on line and see what kind of info you can get from them. They also have local offices in some areas. A lot of the records were destroyed in a fire in 1967 or 1970. It was very true of WW1.
You should also give your local VA a call. They are generally listed with the county for smaller areas. You are generally talking to a veteran and they generally as a rule are very helpful. You could also go down and visit them personally. A face to face personal appointment is always better than a telephone if you can.
In ref. to WW1 we were only in it for a couple of years and that is overstating it. Some people went over and they were back in a year. It did not mean that it was not costly. We lost a lot of men and like war always is. Even if you come back. What kind of shape are you in when you come back. Do you have all of your bodily functions and limbs to make it functional or is your mind still in tact to think with. Did the mustard gas stay with you for the next twenty years or did it kill you later with cancer.
Your relatives might not know; because it is according to what he saw and if he didn't live it every moment after he got out.It is especially true when you try to asleep and when he was awake also. No one generally wants to talk about it; because it is too painful and the memory of the faces To see your buddies lower half no longer there. No war is short. It is according to what you saw and lived every day. That is why no ones knows about his service. He probably just didn't talk about it.
The English and the French and other European countries were in it since 1914. Some of our men served time in Russia after the war was officially over along with a few other countries. Most all the allies contributed in Russia after the war was officially over.