The Dover Barrage was an underwater blockade by England of German submarines attempting to use the

English Channel The English Channel, also known as the Channel, is an arm of the Atlantic Ocean that separates Southern England from northern France. It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busi ...

during

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

. The barrage consisted of explosive mines and

indicator net Constructed using light steel nets, indicator nets were often anchored at various depths to the sea bed around Allied naval bases during both world wars. They were intended to entangle U-boat traffic of the enemy, even though the submarines often ...

s. A similar barrage was used in World War II.

Use in World War I

The barrier consisted of

minefields A land mine, or landmine, is an explosive weapon often concealed under or camouflaged on the ground, and designed to destroy or disable enemy targets as they pass over or near it. Land mines are divided into two types: anti-tank mines, whic ...

laid between

Belgium Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. Situated in a coastal lowland region known as the Low Countries, it is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeas ...

and

Dover Dover ( ) is a town and major ferry port in Kent, southeast England. It faces France across the Strait of Dover, the narrowest part of the English Channel at from Cap Gris Nez in France. It lies southeast of Canterbury and east of Maidstone. ...

at the outbreak of war, followed in February 1915 by 25 km of

s, steel netting anchored to the sea bed. The first evidence of effectiveness was on 4 March 1915, when the German U-boat ''U-8'' was taken, caught in the indicator nets. The first stage of the barrage was completed in April 1915 and it was patrolled by ships of the

Dover patrol The Dover Patrol and later known as the Dover Patrol Force was a Royal Navy command of the First World War, notable for its involvement in the Zeebrugge Raid on 22 April 1918. The Dover Patrol formed a discrete unit of the Royal Navy based at Dov ...

. Both sides initially believed the barrier to be effective and the Germans attributed some submarine losses to it. However, in March 1916, the Germans found their submarines could traverse the Channel on the surface at night. The British moved the barrier to cover Folkestone–

Cap Gris-Nez Cap Gris-Nez is a cape located in Audinghen, a commune in the Pas-de-Calais département of northern France. Part of the Côte d'Opale, it is classified as a protected natural area. Its cliffs mark the closest point of France to Great Britain, ...

and used new mines and

searchlight A searchlight (or spotlight) is an apparatus that combines an extremely luminosity, bright source (traditionally a carbon arc lamp) with a mirrored parabolic reflector to project a powerful beam of light of approximately parallel rays in a part ...

s, effectively closing the Channel to hostile submarines in August 1918. Underwater scanning of the area covered by the Dover Barrage shows the wreck of ''UB-109'' broken in half.

Use in World War II

A mine barrage was also used in Dover during the 1940 Siege of Calais.

References

External links

map showing all known U-boat wrecks from WWI discovered since their loss
{{coord , 51, 3, , N, 1, 36, , E, region:GB-KEN, display=title United Kingdom in World War I Minefields Military history of the English Channel Military history of Kent Dover District