While some philosophers of history have argued that explanations in human history are of a fundamentally different kind than explanations in the natural sciences, I shall argue that this is not the case. Human beings are part of nature, human history is part of natural history, and human historical explanation is a species of natural historical explanation. In this chapter, I shall use a case study from the history of the American Civil War to show the variety of close parallels between natural and human historical explanation. In both instances, I shall argue that these explanations involve narrative descriptions of causal mechanisms. I shall show how adopting a mechanistic approach to explanation can provide resources to address some important aspects of human historiographic explanation, including problems concerning event individuation, historical meaning, agency, the role of laws, and the nature of contingency.