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, designed to compartmentalise the country and delay the Germans long enough for more mobile forces to counter-attack. Over 50 defensive lines were constructed across the country. 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 the last chance of defence.
On the section of the line in Essex, between Great Chesterford and Canvey Island, the defences were made up of around 400 FW3 type concrete pillboxes, which were part of the British hardened field defences of World War II. Well over 100 pillboxes still exist on this section in 2024, with around 40 highly visible FW3 Type 22, 24, 26, 27 and 28 boxes between the Rettendon Turnpike and Howe Green, mostly alongside the A130 road. Many more FW3s are still in place north of Chelmsford along the Chelmer Valley and towards Great Dunmow.