Blyth Battery is a coastal defence artillery battery, built during the First World War to defend the port of Blyth and its submarine base, HMS Elfin. It was up-graded for re-use during World War Two with later additions including an observation post and protection against air attack.
Blyth Battery is unusual because standard military designs had to be adapted to cope with the sandy site. It is also unusual because the buildings have survived and remain remarkably intact.
Particularly special is the World War One magazine, a store for shells and cartridges, complete with electric lighting and spark proof floor. Magazines are normally built underneath gun emplacements, but at Blyth it was separate because the sand dunes affected its construction.
Also special is the World War One Battery Observation Post. Battery Observation Posts acted as look outs and controlled the direction and distance of fire. The armoured turret on the post at Blyth is believed to be the most intact of its kind in the world and includes a rotating cupola for a twelve foot Barr and Stroud horizontal range finder that measures the distance to a target.