The Douglas Convolution

Ian Douglas of 1980, discoverer of the knot in Time, became Captain Gart of 2170 by accident. Once in that role, he dared not change, for the world was fighting a desperate battle for survival. The shattered remnants of the American East were hanging on grimly in the face of maniacal attacks of bestial men. Across the seas a matriarchal order had grasped the fallen reins of science and provided the last hope for a civilized future. Gart/Douglas, with his forgotten skills, could be their best tool. But as a tool he held martial capabilities and scientific abilities they could not suspect. (from the back cover of the first edition)