This page looks in more detail at one of the key Suffolk Stop Lines - The Eastern Command Line.
CRE 11 Corps Operational Order No 1 details the construction of the Eastern Command Line (also known as the Corps Line). It ran from Wivenhoe (Essex) to Mildenhall (Suffolk). It was to consist of a continuous natural or artificial tank obstacle covered by pillboxes. Responsibility for the line from Wivenhoe to Wakes Colne Viaduct was 15th Div Royal Engineers. From Wakes Colne onwards the 11 Corps Royal Engineers were responsible. In Suffolk the line was divided in to three sectors, with a RE Field Company responsible for each sector.
The Field Companies (228, 229 and 230 ) were deployed to the area in July 1940 to start work on the Corps Line. Work continued until September when the War Diaries note a slow down in work and by October no more pillboxes were to be ordered and only those already under construction were to be completed.
The pillboxes were constructed by civilian contractors, the siting of the pillboxes being determined by the Division based in the area. Once sited, RE Field Companies were to hand over the details to the contractors. Contractors were appointed by the Federation of Building Contractors through a District Leader and Group Contractor. The artificial tank obstacle was constructed by 135 Excavator Company, the line of the ditch being given by the RE Field Companies. Tank blocks (e.g. at station Yards) were to be 5 ft concrete blocks at 3 ft 6 in spacing. Small streams and parts of the River Lark were also dammed in places to enhance the obstacle. Road blocks were constructed by County Councils under the supervision of the Divisional Road Engineer of the Ministry of Transport. Direct labour (some unpaid volunteers) was employed in clearing fields of fire, tree felling and trimming up the anti-tank ditch.
Three designs of pillboxes were specified for the line:
C.R.E Colchester Drawing 1116 – to house a static 6 pounder anti-tank gun and a Bren gun. Sited to command main approaches to the line.
Left: Pillbox for 6 pounder anti-tank gun, prob. to design C.R.E 1116
Right: 6 pounder gun mounted in a pillbox
C.R.E Colchester Drawing 1113 – to house an infantry section with one Bren gun. A hexagonal pillbox with 3 ft 6 inch walls. These were sited along the front to command the anti-tank obstacle.
Left: Pillbox with 3 ft 6 inch walls and a central AA well, prob. to design C.R.E 1113.
Middle: Central AA well
Right: Pillbox with 3 ft 6 inch walls but without the central AA well. These have a T or Y shaped anti-ricochet wall instead.
C.R.E Colchester Drawing 1094 – to house an infantry section with one Bren gun. A hexagonal pillbox with 1 ft 6 inch walls. These were sited to protect the front line of Bren gun posts from parachutist attack from the rear.
Above: Pillbox with 1 ft 6 inch thick walls - prob. to design C.R.E 1094
Both of the infantry designs would appear to have two variants – one with a central well with an AA mount (much the same as a Type 27 pillbox) and one without, although no mention of this is made in the surviving records. The new designs as far as can be ascertained (no drawings exist with 11 Corps records) were in effect expanded Type 22’s (C.R.E. 1116 and C.R.E. 1113) or modified Type 28’s (C.R.E. 1094). As well as these ‘new’ designs, other typical designs were also constructed – Type 22’s and 24's.
Guns were apparently only installed in three of the pillboxes designed for the 6 pounder – at Ballingdon Bridge, Sudbury and Southgate and Eastgate Bridges, Bury St Edmunds. Some of the remaining pillboxes were certainly converted to infantry pillboxes by blocking up the main embrasure and installing two rifle embrasures instead.
Above: Main embrasure blocked and two rifle embrasures added
The pillboxes were to be supplemented by Field Works – emplacements for Bren guns, medium machine guns, 2 pounder anti-tank guns and shelters. The siting of the 2 pounder anti-tank guns was carried out with officers from Anti-tank Regt’s – for example Col Danbury from 4th Anti-tank Regt helped with the siting of positions in 228 Field Coy’s sector. First consideration for these Field emplacements was to be concealment from dive bombing.
A central engineer's store was established at Bartlow with supplies transported to the Field Companies sectors by rail.
The Home Guard was to defend the Command Line in the first instance. The key role of the Home Guard was to defend all Nodal Points in their area. If the Nodal Point was on the Command Line any crossing over the Command Line was to be included in any defence plan and held by the Home Guard until relieved by other troops ordered to keep the line. The Home Guard was also responsible for defending any other crossings over the Command Line in their area which was not part of a Nodal Point. Any crossing over the Command Line was to have a written defence scheme produced and the garrison defending it was to be of at least 12-15 men. Commanders of garrisons of crossings over the Commnad Line were expected to send out small patrols regularly to ensure that the whole Command Line was to some extent under constant observation.
If circumstances required, 157 Brigade in 11 Corps reserve and 156 Brigade (part of 2 Corps mobile reserve which could act in support of 11 Corps as well) would occupy the Command Line between the area Bury St Edmunds and Cockfield with the objective of fixing the line and then counter attacking enemy forces advancing south-west from a landing between Lowestoft and Southwold.
Although the construction of concrete pillboxes was halted, work was still being undertaken on the Corps Line in 1941 – 42nd Div was to provide certain towns and villages on the Corps line (and elsewhere) with protective wire obstacles. Villages / towns on the Corps Line to be wired included Sudbury, Bury St Edmunds, Lavenham and Long Melford.
Work also began on organizing the Corps Line as a demolition belt from 1940 onwards. Explosives were placed in pillboxes, provided with locked doors. On ‘stand To’, demolition of temporary farm bridges over the anti-tank obstacle was to commence. Firing parties were to move into place. On ‘Action Stations’ crossings over the Corps Line were to be demolished on Corps orders or if capture was imminent. Rail bridges were not to be blown – rail blocks to be put in place instead. Canal locks were to be held as bridge heads and not demolished - if a canal was to form an anti-tank obstacle the demolition of the lock would deprive the obstacle of its value.
11 Corps papers, TNA
42 Div papers, TNA
52 Div papers, TNA
Pillboxes of Britain and Ireland, M Osborne, Tempus, 2008