I find in the 1930 census that McKinley has "NO" written in column 30, asking is a Veteran of U.S. Military or Naval Forces. According to the ages of McK & Agnes when first married they were married abt 1917, before June anyway.
I also find a newspaper notice in the LeRoy Gazette, (LeRoy, NY) stating that Charles G. Gartley, age 22, son on Deputy Sheriff Gartley and Mrs Hugh Gartley died after surgery for an abscess on the brain. It noted he was one of the first young men of Bryon to enlist in the World War. He was buried March 3, 1920 same date as article printed, he died the previous Saturday. He was survived by parents, 4 brothers and a sister.