I concur that the uniform is not SpanAm era, it is in fact Punitive Expedition pre WW1. But the telling information was the age of Uncle Nickens when the War began, he was 11 years of age when the war started in the year 1898 and 15 during the Phillipine campaigns.In either conflict, the most he could have been was a drumer or muscian and to my knowledge neither the regulars, (Black) nor the volunteers deployed with them. There is a possibilty he may have served in the Punitive expeditions into Mexico, if he had served with the 10th US Cavalry, he would have been 29 years of age.