The system of commercial blockade aiming to exclude England from commerce with the Continent instituted by the Berlin decree, which Napoleon I. issued from Berlin Nov. 21, 1806, declaring the British Isles to be in a state of blockade, and British subjects, property, and merchandise subject to capture, and excluding British ships from all parts of Europe under French dominion. The retaliatory measures of England were followed by the Milan decree, issued by Napoleon from Milan Dec. 17, 1807, imposing further restrictions, and declaring every ship going to or from a port of England or her colonies to be lawful prize.