In the 1770s, the geopolitical significance of differential immunity in the Atlantic American world shifted. Formerly, it had helped stabilize the distribution of territory among the various imperial powers, especially protecting Spain's empire in the Americas. It continued to do so, as the example of Fort San Juan in Nicaragua showed. But now, by the 1770s, it also helped insurgents in their quests to change the imperial order. Political dynamics evolved in such a way that many people born and raised in the Americas sought to upset the status quo. Rebel slaves in Surinam, for example, benefited from differential immunity. In British North America, growing numbers, wealth, self-confidence, and sense of frustration with their treatment by King and Parliament helped turn many Americans onto the path of revolution in the 1770s. A generation later, slaves in St. Domingue and Creole elites in South America also chose revolution. So did Cubans at the end of the nineteenth century. Historians for generations have brilliantly illuminated this age of revolution. One thing that has escaped their spotlight is the role of mosquitoes in making the revolutionaries victorious.