But was it a defeat? Drawing on new material from wartime records-including ultra-top-secret Allied decryptions of German naval radio communications, Roger Sarty shows that Canada mounted a successful defence with far fewer resources and in the face of much greater challenges than previously known. He draws vivid pictures of the intense combat on Canada's shores and the interplay of the St Lawrence battle with war politics in Ottawa, Washington and London. At the same time, he weaves a second story: how researchers reassembled the scattered war records in Canada, Britain, the United States and Germany and brought the long-forgotten battle to life for new generations of Canadians and international audiences.

ROGER SARTY became professor of naval, military, and Canadian history at Wilfrid Laurier University after twenty-three years as a historical researcher and manager for the Canadian government. As deputy director at the Canadian War Museum, he led exhibition development for the new museum building that opened in 2005.