During 1941, consideration was underway to reinforce the A.A. defence of certain Vulnerable Points (VP) and Vulnerable Areas ( VA) in the event of invasion. As well as aerodromes, VA’s subject to reinforcement on Invasion included bottle necks in road and rail communications. In August 1941 some reconnaissance of sites to be occupied in the event of imminent invasion was undertaken although no requisitioning of land or work on gun sites was ordered.
Above: Allocation of A.A. guns under Normal and Invasion conditions in VP’s in Suffolk under defence of 2 A.A. Division.
Lowestoft VA was to be reinforced with 8 mobile 3.7” HAA guns under Invasion conditions (at the time this scale was approved, it was assumed the mobile 3.7” guns at LH1 would have left while statics were under order for LH2, thus the eight guns to come in on Invasion would reoccupy LH1 and a recce was needed for a third four gun site).
In January 1942, the scheme to reinforce the selected VA’s and VP’s when invasion appeared imminent was to be put into effect on the issue of the code word “ATTIC”. The day of issue of the code word was to be known as D.1. All guns were to be deployed and ready for action by 1200 hrs on D.26.
Arrangements were put in place for rail and road movements of guns. All units, sub-units and detachments which were absent, either on training courses under A.A. Command control or Home Force exercises were to be recalled immediately to their normal stations. Concealment of the re-deployment of guns was to be paramount. Orders were issued not to erect tents if they could not be concealed and there was a danger of giving the gun positions away. Guns used to reinforce the selected VP’s and VA’s were to be found by withdrawing them from other VA’s and VP’s.
Guns to be deployed on “ATTIC” in VA’s and VP’s in Suffolk under the defence of 6 A.A. Division.
Instructions for the reconnaissance and preparation at aerodromes for gun sites to be occupied under “ATTIC” and the principles of aerodrome defence were issued early in 1942. It was noted that the R.A.F. was responsible for aerodrome defence and for this purpose the R.A.F. Regiment had been formed and would provide the backbone of the defence. The A.A. Commander was to act as adviser to the R.A.F. Station Commander. Reconnaissance for the defence of aerodromes was to be carried out jointly, involving the R.A.F. Station Commander and other R.A.F. representatives from the aerodrome, the A.A. Commander, Local or Sub-Area Commander and the Superintending Engineer.
The defence plan was to be drawn up to meet the expected type of attack. The A.A. plan was subordinated to the ground defence plan, which had priority in the choice of gun sites. A.A. guns were to assume a ground to ground role as well if necessary, although this was secondary to their A.A. role.
It was expected that it would not be possible to site HAA guns under “ATTIC” within the LAA defence or ground defence system of the aerodrome. They were expected to be self sufficient in ground defence. The War Office had sanctioned the construction of bullet proof walls to be built around gun platforms and the Command Post. When authorized by the War Office, these walls were to be built around all HAA sites on aerodromes on which guns move to on “ATTIC”. If possible, some of the HAA guns were to be sited so that direct fire could be brought on to the surface of the landing ground.
LAA guns were to continue to operate in their normal positions until the notification of “Action Stations”. On “Action Stations”, any aerodrome that was to receive Bofors under “ATTIC”, instructions were issued to move the guns to the troop localities defending the aerodrome and were not to be less that 300 yards apart or more than 600 yards apart so that all guns in any one troop could defend others against dive bombing attacks. This siting would also mean the LAA guns would receive maximum ground defence. As with HAA guns, if possible, some LAA guns should be sited to bring direct fire onto the aerodrome landing ground. As these guns were to move on “Action Stations”, instructions were issued to prepare for the “Action Station” positions for the full number of LAA guns allotted under “ATTIC”. It was recognized however that insufficient labour in A.A. Command was available to construct these numerous LAA positions. The R.A.F had agreed to provide some support.
As LAA guns were to have an important secondary ground defence role, they would be expected to be able to engage AFV’s or enemy troop carrying aircraft which had landed. This required positions to have a low parapet, which contradicted with the need for a high parapet to give maximum protection against low level flying attacks. To overcome this contradiction the following instructions were issued for the construction of the “Action Station” positions:-
Prior to “Action Stations”: Gun sites to be constructed so that they could engage AFV’s from any direction. Revetment to this height was to be of permanent material such as concrete blocks. These should be turfed or sown with grass. Positions should be square as experience from Malta had shown round positions were easily identifiable from the air. Simple ammunition recesses were to be constructed.
On “Action Stations”: Parapets to be increased so as to provide protection against low flying aircraft attacks. This was to be done with a bullet proof sandbagged wall on the existing parapet. They were to be built up so they could be removed quickly, on the warning being received that AFV’s were approaching.
Camouflage of these “Action Station” positions was paramount. Netting should be erected over the sites before any work commenced.
Reinforcing guns under “ATTIC” were not to open fire until a major attack took place on the aerodrome in order not to disclose their positions. It was expected that the enemy, prior to a major attack, would at first send in a few aircraft with the aim of encouraging the A.A. defences to expose their positions.
During 1942, A.A. Command was in crises due to having to meet the needs for A.A. defence against the “Baedeker” raids, “Tip and run” raids and protecting ports involved with the first stages in the planning of the allied counter-offensive. The deployment of mobile equipments to historic cities and coastal towns and some ports left other areas with inadequate protection or even undefended: The Chiefs of Staff reported they could not “view the present situation without grave misgivings, since not only is A.A Command below that figure which was …considered a bare minimum consistent with reasonable security, but also … we have been forced to denude the Midland and Northern gun-defended areas and vulnerable points of anti-aircraft guns, with the result that industries, ports, and aerodromes in those areas are at the present moment either not defended at all or are left with a number of guns inadequate to ensure a reasonable scale of protection”.
General Sir Frederick Pile noted that these deployments to ancient towns, coastal towns etc made “complete nonsense” of the “ATTIC” scheme. General Pile also noted that he agreed with Churchill’s view that invasion was unlikely and as a result in July 1942 suggested that all anti-invasion planning be suspended and accordingly A.A. Command ceased to continue with anti-invasion planning. Given that anti-invasion preparations drew to a close in July 1942, it is uncertain how many “ATTIC” gun sites were prepared.
2 A.A Division papers, TNA
6 A.A Division papers, TNA