Confined to a nursing home in Iowa in 1960, a time-worn horseman seeks to educate his grandson about the great transformation in American agriculture when horse power gave way to tractor power (1910-1950). Walt Decker spent nearly four decades as the chief national defender for the continued use of draft horses on the farm, especially Percherons. His grandson Jethro is a student in agricultural engineering at Iowa State University and does not understand the significance of the shift from equine power to tractor power. Grandfather Decker seeks to teach him with seven historical lessons that tell the story of this remarkable transformation as well details about the tractor wars that erupted after Henry Ford introduced his famous Fordson tractor in 1918. The historical lessons are nested in a series of letters from grandfather to grandson in which Walt Decker seeks to bridge the chasm of mistrust that exists between Jethro and himself. This is a work of history and historical fiction. It is enhanced by dozens of illustrations and archival images, along with a bibliography of suggested readings. Walt Decker has been loosely modeled after Wayne Dinsmore (1879-1966), longtime secretary of the Percheron Association of America and then the Horse and Mule Association of America.