The Anglo-American relationship across the long nineteenth century was one that was marked by the periodic oscillations between confrontation and cooperation. While the discourse between the leaders of either nation was marked by a kind of gentlemanly civility any sort of linear approach to the emergence of the “Special Relationship” of the mid-twentieth century obscures the significant transformations in transatlantic diplomacy during the nineteenth century. North Atlantic fisheries played a key role as transatlantic relations tacked between agreement and discord during the nineteenth century. This single issue allowed for and created the conditions necessary for addressing myriad other concerns and in the process continually redefined the relationship. The significant pivots in Anglo-Americans relations were in one manner or other intimately tied to the fisheries. Introducing the fisheries issues will demonstrate how, for instance, the Convention of 1818, the Reciprocity Treaty of 1854, and the Halifax Commission were the most vital junctures in transatlantic relations. This narrative of Anglo-American relations would remain obscured without an appreciation for the fisheries and the role of the environment more generally. While environmental history has long appreciated how proceedings in the human world were influenced by the natural, or nonhuman, world, diplomatic historians have been slow to consider that nexus. The transformations that are the focus of this dissertation would be invisible without the environmental lens. Fishermen, in addition to the fish they sought, are likewise important actors in this story as the on the ground, or perhaps water, decisions they made influenced the course of diplomacy at every level