Soccer players may get all the glory, but behind every great player is a great coach. And behind every great coach today stands a deep fraternity who dedicated decades to supporting soccer's long climb from obscurity to become one of the major sports in America. It was an uphill battle, fought persistently and creatively to overcome a public perception of soccer as "foreign," "aloof," "snobby," or simply "odd." This is a story of individual and collective action, of coaches coming together to improve the sport and expand its reach. From coaching methodologies to standardizing rules, improving the play on the field and the perceptions beyond it, persistent coaches were instrumental in creating the game played and watched today. Relentless tells the landmark and previously untold stories of resolute coaches, their love of the game, and how they transformed the sport in the United States.