Northern Patrol
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. First World War. In 1904, ten years before the start of the First World War, the British naval War Plan saw Germany as the main potential enemy. The War Plan included a distant naval blockade to cut trade to and from Germany, including goods carried in neutral vessels. In case of war with Germany, a special naval force was to patrol the sea routes between the north of Scotland and Norway and intercept traffic from the Atlantic into the North Sea. The force was named Cruiser Force B or the Northern Patrol Force and operated under  the authority of the commander of the Grand Fleet in the First World War and the Home Fleet in the Second World War . It was to operate from Scapa Flow in the Orkney Islands. The force was later renamed the 10th Cruiser Squadron. The Admiral Commanding, Orkneys and Shetlands was established at the outbreak of hostilities in 1914 to run the Grand Fleet's principal base at Scapa Flow, which included the local defence forces for the base. The Northern Patrol operated within this command but its relationship to this shore command is unclear. By 1914 the Northern Patrol was  to comprise eight Edgar class cruisers from the reserve fleet, some of the oldest in the Navy, to be augmented with armed merchant cruisers as soon as suitable merchant vessels had been converted. With war between Great Britain and Germany expected to break out any moment, the 10th Cruiser Squadron was mobilised on 1 August 1914 under the command of Rear-Admiral Dudley de Chair. The first cruisers arrived at their Scapa base on 6 August 1914, two days after Britain declared war on Germany; operations started on 9 August 1914. At first the area to be patrolled was from  the Shetland Isles eastwards to the Norwegian coast and southwards to Scotland. The Edgars were poor sea-keepers and with old and unreliable engines were soon found unsuitable for operations with the Northern Patrol. In mid-August 1914 the first armed merchant cruiser started operations with the Northern Patrol and soon enough AMCs were available to recall the surviving seven Edgars ( had been lost in October 1914) on 20 November 1914. The AMCs had better sea-keeping and more reliable machinery than the Edgars and provided their crews with far more comfortable quarters. Later, armed trawlers were added to the  force and warships from the Grand Fleet or other commands were sometimes temporarily attached to the patrol. Admiral De Chair was replaced early in 1916 by Rear-Admiral (later Vice-Admiral) Reginald Tupper. Tupper commanded the 10th Cruiser Squadron until it was abolished in November 1917. By then the entry of the United States, the main source of contraband, in the war drastically reduced the need for the blockade. The ships of the force were reassigned to convoy and anti-submarine work. The ships of the Northern Patrol inspected almost 13,000 merchant vessels at sea. Only 642 ships managed to  penetrate the blockade without being inspected. The force lost one cruiser and ten AMCs. The blockade is generally considered to have been one of the main causes of the defeat of Germany in the First World War. Second World War. The Northern Patrol was re-established on 6 September 1939, three days after the start of the Second World War. Its area of operations was more extensive than during the First World War and included the areas north of Scotland and Ireland, between the north of Scotland and Norway, around Shetland, the Faeroe Islands and Iceland and the Denmark Strait , between Iceland and Greenland. As in the First World War, older cruisers from the reserve fleet made up the original units of the new Northern Patrol, four C-class and four D-class light cruisers, with the heavy cruiser as flagship and for a short time the two light cruisers of the E-class; Armed merchant cruisers soon replaced those. As in the First World War, warships from the Home Fleet or other commands were sometimes temporarily attached to the Northern Patrol. The force continued to operate within the Orkneys and Shetlands Command but was not under the admiral commanding . Components. Note: These squadrons were supplemented and then replaced by armed merchant cruisers which operated until dispersed or sent to other duties between 1940 and 1941.