In the summer of 1816, a single red-hot cannonball fell into the powder magazine of a fort on the Apalachicola River, and some two hundred and seventy free Black men, women, and children died in an instant. It was the opening act of a war the United States would fight for forty-two years and never truly win. American textbooks divide this struggle into three short Seminole Wars separated by years of peace. The people who lived through it knew better. Across swamps, prairies, and treaty councils, the Seminoles and their Black Seminole allies endured an unbroken campaign of invasion, dispossession, slave-hunting, and betrayal under flags of truce, a conflict they call the Long War. Marcel Grogan traces that war from the ruined missions of colonial Florida to the Everglades hammocks where the last holdouts refused every offer. Here are Osceola dying in a fort in Charleston harbour, Coacoochee squeezing through a fortress window, John Horse leading his people across Texas to freedom in Mexico, and Polly Parker walking four hundred miles home from a deportation steamer. Richly told and unflinching, this is the story of the costliest Indian war in American history, and of a nation that was never conquered.