In May 1940, the prospect of imminent invasion of Britain led to the creation of the Home Defence Executive under Sir Edmund Ironside. The fall of France followed shortly afterwards, requiring the preparation of a strategy for the defence of the island by a small mobile reserve and limited support from fixed defences and the newly-formed Home Guard.
The
creation of a ‘coastal crust’ of defended and obstructed possible landing
sites was supplemented by a series of ‘stop lines’, exploiting natural
barriers enhanced by obstacles and strongpoints, to delay an invasion force
and protect the central areas (Wills 1985).
The most significant of these lines was the GHQ line, running from
Edinburgh and Bridgwater to London. In
Wales, successive rivers were chosen, including the Rivers Wye, Usk, and Neath
(Locock 1994; Kerr 1994). The
limited number of crossings were protected by pillboxes, and arrangements were
made for the demolition of unwanted bridges.
In
June 1940, a new military formation was created, ‘Auxiliary Units, Home
Forces’, to operate as a guerilla force ‘to act offensively on the flanks
and in the rear of any German troops who may obtain a temporary foothold in
this country’ (PRO WO 199/738). To
perform this role, small teams of ‘local men who know their countryside
intimately’ were recruited from the Home Guard and given specialist training
in sabotage. The Units were
organised into patrols, a leader and six men, and each patrol had a specially
- constructed Operational Base (also called a hide or hide-out), usually
hidden in woodland, to store munitions and to occupy in the case of invasion;
it was envisaged that the patrol would lie up during the day and emerge at
night to carry out its activities (Bradford 1992).
In order to preserve secrecy, the Auxiliary Unit structure was kept
separate from the local command
and the Home Guard, and the recruits were encouraged to conceal their role
from their friends and families.
THE
AUXILIARY UNIT OPERATIONAL BASE
The primary requirements for the OB were that they should be concealed, habitable and reasonably weatherproof. A standard design was used, comprising an underground chamber, roofed with corrugated iron; the end walls were brick, with a brick shaft at one end leading to the main entrance, and an escape at the other end with a second brick shaft, measuring c. 2.5m x 4.5m (PRO WO199/1517). The shafts were concealed by camouflaged trap-doors. Because of the camouflage and secrecy associated with these buildings, they are poorly represented in records of known sites from the period (see for example Locock 1996).
The example at Cilybebyll, in woodland 100m northwest of Plas Cilybebyll house (SN 750 043: it is on private land), survives in good condition (fig. 1); the author was invited to investigate the site by the landowner. On the surface, the OB is visible as a slightly-raised area; at the north end, the shafts are visible as brick features, no longer hidden by a trap door. There is little doubt that when constructed it would have been concealed from all but the closest scrutiny (fig. 2).
The
interior now has a flooded floor. A
winch arrangement on the entrance wall survives; this may have been attached
to an aerial for radio communications or to the trap door. An alcove on the east side of the door may have been for the
radio equipment.
Figure 1: Interior showing corrugated iron roofing and escape opening.
Figure 2: The surface, showing escape shaft
THE
ROLE OF THE CILYBEBYLL SITE
Although no documentary
evidence for the OB has been located, its location is significant, in wooded
land to the north of the Neath valley. Had
an invasion force arrived in southwest Wales (perhaps using Milford Haven as a
deep-water harbour, and perhaps starting from Eire, as was feared at the
time), it would have encountered resistance at Carmarthen - New Quay (Glover
1990), Ammanford, the River Loughor, the Swansea valley, the Neath valley and
the River Taff (Redfern 1998).
Each
stop line would have forced a delay while a set-piece assault was prepared.
If the small number of bridges strong enough to take tanks were
demolished, temporary engineering works would also have been required; one of
the key functions of the pillboxes guarding river crossings was to prevent
their seizure by parachute forces to forestall their demolition.
Thus
it was planned that the invading force would have been held up on the west
bank of the Neath valley for days or weeks; in the meantime, the Auxiliary
Unit patrol would have numerous opportunities to cause further disruption and
delay.
The
occasion for use did not occur; there was some discussion in the latter stages
of the war about the future of the OBs, along with the disbanding of the
Auxiliary Units (PRO WO 198/738), and although demolition of the sites was
proposed, many seem to have been simply abandoned, and survive as monuments to
a short period when the tranquil landscape of the Neath uplands was viewed as
a possible battle zone.
Acknowledgements
The
author is grateful to Richard Bowen of Plas Farm, and to Roger Thomas (English
Heritage) and Jenny Hall (Cambria Archaeology) for their assistance with the
research.
References
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G, 1992, The British resistance movement, 1940-44, Secret Armies 51.
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