In 1852 controversy arose between Great Britain and the United States over the right of American fishermen to ply their trade off the British North American colonies, necessitating the dispatch of an American warship under Commodore Matthew Calbraith Perry to survey the fishing grounds and negotiate with the local authorities. This incident provides an opportunity to explore how Anglo-American diplomacy both helped prevent a resurgence of conflict after the end of the War of 1812 as well as how it influenced Perry’s later Japan expedition of 1853-1854, demonstrating the contemporary importance of the colonies as an Anglo-American geopolitical fault line.