I finished reading Bill Shea's new book on Prairie Grove, and can only say that it matches the high standard he set with his Pea Ridge book. Great job, Bill!
Out of curiosity I researched Lt. Col. John A. Geoghegan of Pleasants's AR regiment, and will share my findings with everybody here. His full name is John Andrew Geoghegan, born 12-23-1823 Richmond, VA, son of Charles and Ellen (Kendall) Geoghegan. Attended U of PA Medical school and became a physician. He was in business with his father in tobacco and shipping in Clarksville, VA. He moved to AR in 1859, and in 1860 he's a physician in Dallas County. His compiled service record has him captain co. E, 37th AR 5-8-62, promoted major 6-6-62 and to Lt. Col. 6-12-62. Resigned 12-18-62 right after the Battle of Prairie Grove, citing hemorrhoids. Resignation accepted by General Hindman with the notation that Geoghegan "is not and never will be competent." Moved back to VA and NC postwar. Died 4-16-1896 Warren Co., NC. Married 1) Ann, d/o Robert Jones of Person Co., NC; 2) Mary Louise Fuller. Several children. Bill, Alan and all, hopes this helps.