The policy laid down for the defence of beaches where a landing was possible was that they should be covered by a variety of obstacles (wire, mines, tank blocks etc). Maximum use was to be made of concrete pillboxes to cover these obstacles. Field works were to be constructed to cover the flanks of these pillboxes. Defence works were expected to be sited to cover the approaches from the rear to meet attacks from airborne enemy troops. If pillboxes were not capable of this, field works would have to be provided for the weapons normally emplaced in the pillbox (anti-tank rifles and light machine guns). Field works were also to be incorporated in the local defence scheme for any coastal guns.
In 1940 the standard field work from which defensive fire could be delivered from was still the fire trench. Short lengths of fire trench were connected to a pillbox or linked with communication trenches. In Suffolk there appears to be at least one example of a platoon locality comprising of pillboxes, fire trenches and dug-outs all linked by communication trenches.
Field Enginnering manuals show the construction of fire trenches in three stages. Stage I was basically the weapons-pit, which was usually dug to accommodate two men. These pits would be dug to cover the given fire task of the section post. In the initial stages of construction the pits may have been linked by crawl trenches. The weapons-pits would then be completed to stage III i.e. the fire trench and the crawl trenches deepened to communication trenches.
Above: left - Weapons-pit and Crawl trench. Right - Weapons-pits linked with Crawl/Communication trenches to form a
The components of a fire trench were:
- Parapet – this should be at least 5 ft thick and a min of 18 inches high. The top should not be flat and even but as irregular as possible to help conceal its outline. The parapet should slope gently to the front.
- Parados – this was to protect the firer from splinters of shells bursting behind the trench and to provide a background so that the heads of firers are not siloutted against the sky or light coloured background.
- Berm – this is the space between the parapet or parados and the edge of the trench. It should never be less than 12 inches and was essential to prevent the excavated earth on the parapet or parados from falling into the trench.
- Fire step – this should be a least two ft wide and if possible revetted.
Above: left - stages in construction of a Fire trench. Right - two photos of trenches (top photo is somewhere in Britain, 1939). Bottom photo is an
often seen image of trenches on a beach, Great Yarmouth.
Trenches would be could be revetted either with ‘A’ frames or pickets with brushwood or sheeting. The War Diary of the 6th Kings Own Scottish Borders makes reference to a plentiful supply of 'A' Frames and chestnut pailing for revettment. On the other hand, CRE 42nd Division noted difficulty in getting it's quota of revetting material with the result that it reported to 15th Division when handing over that some section posts may need revetting.
The object of a communication trench was concealement and protection. It was also vital that some sections of communication trench were prepared so that fire could be delivered from them in any direction in the event of penetration of the defences.
Communication trenches were initially to be dug to 3 ft deep and 3ft 6 inches wide and if time allowed deepened to allow men to walk upright without exposure (approx. 7 ft deep). To ensure protection of enfilade fire the trace of the trenches should be irregular i.e. “winding”. There should be parapets on both sides of the trench with a berm of 1 ft 6 inches.
It is interesting to note that by the end of 1940, the War Diary of 125th Brigade, 42nd Division, notes that intercommunication trenches around pillboxes were no longer to be maintained (although fire trenches and grenade pits were to be kept in a state of repair).
Right: Trace and sectiion of communication
trench (which has been revetted with an 'A'
Below are two plans of surviving Field Works in Suffolk.
Above: left - plan of a platoon locality consisting
of three pillboxes, fire trenches and dug-outs all
linked with communication trenches. Right - aerial
photo of the trenches.
Below: plan of a section post consisting of short
lengths of fire trench linked with short lengths of