I believe you are speaking of the US draft registration. The radicals just wanted to inventory the military age men of Kentucky for possible future military service in the Federal army. There are many cases of men being forced to participate in the draft registration fearing the possible future forced service in the Yankee army going ahead and entering the Confederate army. John A Berryman shows up in June 1863 Graves County, KY, draft registration and in July 1863 joins the Twelfth Kentucky Cavalry, CSA as 2 Lt. and being paroled in May 1865 as 1 Lt.