There was an Alonzo Bentley born 1899 (30) in GA living in Detroit, MI with his wife Virginia (31) in 1930.

Census > U.S. Census > 1930 U.S. Federal Census > Michigan > Wayne > Detroit (Districts 1-250) > District 78

That Census said he was a veteran and had served in the W. W. which I assume means World War.

Which Census/which state did you see the 5 year reference in. Surely, if was born in 1899, he could not have served 5 years by 1910, when he would have been only 10 or 11? Or is the 1899 date a typo?