The definitive history of submarine warfare off the North American coast in the summer of 1918. When America declared war on Germany in 1917, it unleashed a resumption of unrestricted submarine warfare off the North American coast. Until now, German naval records have not been extensively utilized in English-language histories of this brief but intense period of naval combat in the Atlantic. By studying and comparing both American and German archival sources, author Dominic Etzold has constructed the first balanced narrative history of the operation that is equally engaging, modern, and revelatory.