Eugene Ware's book was published in 1911, just after Ware's stint as Commissioner of Pensions (1903-05). During those first few years of the 20th Century veterans of organizations (Union) which had served their entire enlistments on the Plains were being frustrated getting pensions since they served DURING the Civil War, but not IN the Civil War (or "Rebellion"). I'm uncertain whether Ware faced this head-on for it didn't arise strongly until 1908-'09 (-ish). By the time Ware wrote "Indian War of 1864" it was obvious that linking the Indian Wars with the Southern Rebellion would smooth the way for those veterans who had "only" fought Indians. So, I think Ware deliberately overstated the case in his book, but was there the possibility that Confederate agents stirred-up the central and northern Plains tribes? Of course, but there was a long list of grievances with the Federal government that might have led to Indian outbreaks completely absent Confederate interference. Love to know what you think of this theory!