Volume I of Know Thine Enemy presents a history of the political philosophy that is known throughout the world today as "the Left," which grew out of an effort by revolutionaries in eighteenth-century France to replace the "superstition" of Christianity with a secular social and moral system based on reason and science. The book traces the development of this project through many stages, beginning with numerous efforts in Europe to build a working model for a socialist utopia, moving on to the creation and eventual failure of Marxism, and finally, to the many efforts to revise the Marxist model, which prepared the way for the emergence of fascism in Italy and National Socialism in Germany.

It also traces the early development of American's homegrown brand of socialism, the introduction of European socialism in the post-Civil War migration of workers from Europe, and the subsequent advent of Progressivism and liberalism.

The purpose of the book is to acquaint readers with an intimate and comprehensive appreciation of the views and efforts of the heroes in the almost three-century-long assault on Western Values, whose actions, speeches, writings, and aspirations collectively form the foundation of American conservatism. In doing so, it hopes to strengthen, reinforce, and yes, refine the readers' existing conservative beliefs, and thus help in the fight against the common foe, because the fate of the nation and, indeed, of Western Civilization itself, depends upon it. As the great Chinese general and military strategist Sun Tzu famously said over 2,500 years, "If you know your enemy and know yourself, you need not fear the result of a hundred battles."