This dissertation analyzes the historical production of the southern highlands of Aceh (Indonesia) into the Leuser Ecosystem; a dialectical space of nature imagined to be both pristine and imperiled. The Dutch began to imagine Leuser as a space of nature following more than forty years of war (1873–1913) with the people of Aceh. Officials viewed both the colonial institution and the ecologies of Leuser to be under threat due to local resistance and the wildlife trade. Militarization, scientific practices, and environmental conservation are examined together to show that Leuser was a center of state-making and empire during the colonial period. It was a space where military leaders, conservationists, and scientists collaborated in attempts to physically, discursively, and legally erase Indigenous peoples from the land. Through this inquiry, I argue that military leaders in Aceh appropriated conservation as a tactic for counterinsurgency. With this in mind, I ask what might the relationships between militarization and conservation tell us about colonialism? How can a history of Leuser, as a region, revise the narrative of Aceh’s history? When, and how, did Leuser become a space of nature with “universal value” on a global scale, to be secured with militarization? What does the historical construction of Leuser tell us about the production of the Nature/Society binary? In offering answers to these questions, I contend that the erasure of Indigenous histories, the transformation of Leuser into a space of imperiled nature and militarized ecologies, and an enduring environmental crisis have served to legitimize and facilitate dominant forms of land management since the early twentieth century. This manuscript is organized into five chapters that each tell a history of how Leuser was produced into a space of nature separated from society. The chapters interrogate legacies of militarization, scientific exploration and bioprospecting, the origins of primatology and the violence of field science, the wildlife trade and the West’s obsessions with Sumatran species (most notably the orangutan), and the rise of the international nature protection movement. The construction of nature is examined at different scales and from different perspectives and brought together in a woven narrative.