1474: First Chess Book
Luis Ramírez de Lucena of Salamanca, Spain published the first true book about the game of chess: Repetición de Amores y Arte de Ajedrez ("Repetition of Love and the Art of Playing Chess" - link to actual book). While other earlier books referenced chess, this was the first book that included the modern rules and explained the key strategies, tactics, openings, and endgames of chess.