“There is a broad consensus among professional historians that the Vietnam War was effectively unwinnable. Even the revisionists admit their minority status, though some claim that it’s because of a deep-seated liberal bias within the academic history profession. But doubts about the war’s winnability are hardly limited to the halls of academe. One can readily find them in the published works of official Army historians like Dr. Jeffrey J. Clarke, whose book “Advice and Support: The Final Years, 1965-1973” h