Roger Sarty, one of Canadas foremost military historians, is the former Senior Historian at the Directorate of History, National Defence Headquarters. He currently holds the position of deputy director of the Canadian War Museum and the author of Canada and the Battle of the Atlantic and No Higher Purpose: The Official Operational History of the Royal Canadian Navy in the Second World War. Ottawa military historian Doug Knight is a retired Canadian Army officer. His engineering experience provides a solid background for his research into the history of Canadian military equipment and fortifica...