U-Boats: Hitler's Sharks

From the outset of World War II, control of the seas was the key factor in the military strategy of both the Allies and the Nazis. By blockading the waters around the United Kingdom, Germany sought to deny Great Britain its critical shipments in an attempt to suffocate them. While the strategy worked successfully at the start, Hitler made a tactical error when he refused to provide his U-Boat commanders with additional submarines.