Book excerpt: This is another Civil War history book, but it deals with an aspect of the Civil War that does not appear-even as an aside or footnote-in the vast majority of the other fifty thousand books and pamphlets that address that war. This is the untold story of the complicated cross-border, multi-sided Civil War era specific to the Rio Grande Valley in both Texas and Mexico that took place most intensively between 1861 and 1867, yet the roots of which reach back to at least 1846 and extend forward to at least 1877.