The career of Julius Philip Benjamin von Rohr, a German botanist in Danish colonial service, embodied many of the scientific, economic, and moral concerns of his times. He was born in Merseburg, in Prussia, in the 1730s, studied natural history and medicine in Halle, and emigrated to Denmark as a young man, apparently to escape the Seven Years’ War. In 1757 the Danish government sent him to the Danish West Indies (which are now the US Virgin Islands) to serve as public land surveyor. His rather unusual commission also called on him to study the islands’ natural history. The Crown had lately taken over the administration of the colony from the Danish West India and Guinea Company, and the slave-plantation economy of St Croix, the largest of the islands, which had been settled by the Danes in the 1730s, was beginning to boom when von Rohr arrived. The island was transformed in his time there: in 1750, perhaps half the acreage of the island remained in woods and bush; thirty-five years later, the island was cultivated essentially from end to end. Von Rohr also served as the island government's architect, building engineer, and construction supervisor; he spent most of the rest of his life in the West Indies.

Although von Rohr's career was launched out of an elite Copenhagen circle of German expatriates and German-speaking Danes from the kingdom’s southern duchies, he became a true citizen of the Atlantic, an Enlightenment scientist of international repute, with extraordinary personal experience of the tropical world and far-flung intellectual connections. He was an enthusiastic natural historian, but he was also a diligent and trusted government official, and some of the main colonial ideas and ambitions of the Danish state at this period found expression in the work he was asked to do. An examination of the last decade or so of his life, in particular, opens unusual new North-Western European perspectives on the plantation world of the Atlantic at the start of a period of profound transformation, when societies began to turn away from slavery and its fruits.

Natural History in a Colonial World

The study of natural history in the eighteenth century encompassed far more than botany and zoology and mineralogy.