Petty’s field books illuminate a troubling connection between administrative knowledge and power: detailed measurement allowed officials to convert conquest into allocations for soldiers and adventurers, while everyday rural relationships remained less visible. The article suggests that uneven transplantation did not lessen its significance, since altered ownership, tenancy and patronage could reshape communities even where formal removal was incomplete. It is also striking that this technical survey coincided with religious repression and competing Protestant interests, revealing settlement as more than a land question. How might historians weigh the Down Survey’s cartographic achievement against its role in creating long-term insecurity across Ireland?