I am looking in the historical section of the Iowa Adjutant General's report of 1866 for the Eighth Iowa Cav. So far I have not found any mention of capture of any flag or colors, though once or twice during the Nashville campaign in late 1864 the Eighth claimed taking several hundred prisoners and stands of arms. I'll let you know if I find anything else. Would this "large Second National" flag be a regimental colors or a garrison size?