The Northern Patrol, also known as Cruiser Force B and the Northern Patrol Force, was an operation of the British Royal Navy during the First World War and Second World War. The Patrol was part of the British "distant" blockade of Germany. Its main task was to prevent trade to and from Germany by checking merchant ships and their cargoes. It was also to stop German warships, raiders and other German naval ships from leaving the North Sea for the Atlantic Ocean or entering the North Sea from the Atlantic, protect Shetland against invasion and to gather intelligence from intercepted neutral ships.

The Blockade of Germany, or the Blockade of Europe, occurred from 1914 to 1919. The prolonged naval blockade was conducted by the Allies during and after World War I in an effort to restrict the maritime supply of goods to the Central Powers, which included Germany, Austria-Hungary, and the Ottoman Empire. The blockade is considered one of the key elements in the eventual Allied victory in the war. In December 1918, the German Board of Public Health claimed that 763,000 German civilians had already died from starvation and disease caused by the blockade. An academic study done in 1928 put the death toll at 424,000. An additional 100,000 people may have died during the post-armistice continuation of the blockade in 1919.