In dramatizing the loss of Lancastrian control in France, Shakespeare's Henry the Sixth plays draw attention to England as an island made as much by human activity as by geomorphology. By focusing on characters' varying engagements with the English littoral—the margin where land meets sea, and where local, national, and transnational interests intersect—this article considers the political and ecological consequences of England's dynamic insularity. Reading Shakespeare littorally reveals contested visions of Great Britain's evolving role in the changing tides of the late sixteenth century and suggests a model for adaptive, global citizenship amidst the political and environmental precarities of the twenty-first.