At the beginning of the nineteenth century, Baron Roger built a castle in Senegal and laid out the fields of an experimental farm around it. The folly of a dream of conquest and domination was intertwined with a conception of agriculture as a strategy of occupation. Over time, the farm became a fort. It housed governors, botanists and, through them, the various systems of power and domination put in place to colonise Senegal. We follow the wars and conflicts between the colonists, the Braks and the Linguères of Waalo, the battle between Governor Faidherbe and Ndaté Yalla’s army and the war that marked the beginning of the colonisation of Senegal. In the wake of this battle and the conquest of Waalo, the folly regained its function as a farm and the project of agricultural occupation of the land attempted to resume its course, although the plants, the Waalos and the soil all continued to resist the occupation.