William Walker's Wars: How One Man's Private American Army Tried to Conquer Mexico, Nicaragua, and Honduras

In the decade before the onset of the Civil War, groups of Americans engaged in a series of longshot—and illegal—forays into Mexico, Cuba, and other Central American countries in hopes of taking them over. These efforts became known as filibustering, and their goal was to seize territory to create new independent fiefdoms, which would ultimately be annexed by the still-growing United States. Most failed miserably.

William Walker was the outlier. Short, slender, and soft-spoken with no milit...