My G-grandfather was William Richard Carroll, who I think served in the 4th Arkansas Union Cavalry. His son, B. C. Carroll, who was born several years before the civil war, married Anna Harkey from Harkey Valley, Yell County, Arkansas. Several Harkey's served in the 3rd Arkansas Union Cavalry. They were all "Mountain Feds." As a Christmas gift to my "Carroll" side of the family, I would like to provide them with some additional info on the above Carroll/Harkey guys, particularly William R. Carroll. The family seems to know little about any of their service in the Civil War. Can anyone verify what company any of them served in and their commanders? Thanks.