The surprising story of how Thomas Jefferson commanded an unrivaled age of American exploration—and in presiding over that era of discovery, forged a great nation. At the dawn of the nineteenth century, as Britain, France, Spain, and the United States all jockeyed for control of the vast expanses west of the Mississippi River, the stakes for American expansion were incalculably high. Even after the American purchase of the Louisiana Territory, Spain still coveted that land and was prepared to employ any means to retain it. With war expected at any moment, Jefferson played a game of strategy, putting on the ground the only Americans he could: a cadre of explorers who finally annexed it through courageous investigation. Responsible for orchestrating the American push into the continent was President Thomas Jefferson. He most famously recruited Meriwether Lewis and William Clark, who led the Corps of Discovery to the Pacific, but at the same time there were other teams who did the same work, in places where it was even more crucial. William Dunbar, George Hunter, Thomas Freeman, Peter Custis, and the dauntless Zebulon Pike—all were dispatched on urgent missions to map the frontier and keep up a steady correspondence with Washington about their findings. But they weren’t always well-matched—with each other and certainly not with a Spanish army of a thousand soldiers or more.