GHQ Line

The GHQ Line (General Headquarters Line) was a defence line built in the United Kingdom during World War II to contain an expected German invasion.

The British Army had abandoned most of its equipment in France after the Dunkirk evacuation. It was therefore decided to build a static system of defensive lines around Britain, all designed to compartmentalise the country and delay the Germans long enough for more mobile forces to counter-attack. Over 50 defensive lines were constructed around Britain. After the coastal defences, the GHQ Line was the longest and most important, designed to protect London and the industrial heart of Britain and was considered to be Britain's last chance of defence.

The GHQ Line - green ran from the northern end of the Taunton Stop Line near Highbridge in Somerset, along the River Brue, across the Mendips from Wells and following the railway from Masbury into the Wellow valley. This joined the GHQ line - blue which followed the Kennet and Avon Canal to Reading. The green line continued from Bradford-on-Avon along the river to Malmesbury where it met the GHQ line - red which headed for Abingdon, along the Thames to Pangbourne and rejoined the blue line at Theale. The green line continued to Avening then down the valley to Framilode, thus encapsulating the strategic areas of Bristol, Avonmouth, and Sharpness. Lines A, B, and C ran in concentric circles around London, with the outer line A running south of Guildford and Aldershot being the most comprehensive. The Eastern Line ran inland of the coast from Essex to Edinburgh.

...
Wikipedia