3The final volume in this highly acclaimed series ushers in the twentieth century, the bloodiest in world history, and arguably the century that saw more accelerated and profound changes than any previous era. The book begins by examining the vicious competition among nation-states for political and military dominance. It then expands its focus to consider the impact of new technological developments and artistic and philosophical ideas, including the discovery of relativity and innovative interpretations of the human mind. It concludes by discussing the lasting impact of colonialism, the rise of identity politics, and the new era of accelerated globalism.