Many historians consider the Spanish-American War to be a conflict that American journalists not only reported but helped create. The United States had complex motives for going to war against Spain in 1898; sympathy for its Cuban neighbors mixed with the nation's own global ambitions. But Americans were also driven to war by their emotions, stirred by a series of newspaper stories.

For decades, Cuban patriots had waged guerrilla warfare against Spanish rule. Outnumbered and poor, the revolutionaries tried to disrupt the Cuban economy by burning sugarcane plantations. The Spanish retaliated harshly, executing suspected rebels and herding peasants into camps where thousands succumbed to disease and starvation. These brutal measures provided stirring copy for American journalists, who invariably sympathized with the Cuban underdogs.

Still, the public might have paid little attention to the conflict had it not coincided with a newspaper circulation war in New...