The Elan Valley involvement in two wars
World War 1
The first encounter that the Cwmdauddwr Hills had with the British Army was in September 1903 when 13 trains arrived at Rhayader station from Swindon carrying 434 men, 138 horses and 6 heavy guns of the Royal Artillery. The Lion Royal hotel, Rhayader, was the HQ for the officers whilst other ranks were billeted in a tented camp in the fields near Nannerth Fawr, Cwmdauddwr. The horses pulled the guns to the top of Penrhiwen, three miles outside Rhayader on the mountain road to Aberystwyth. The War Office had decided to test a new firing range with a view to replacing the ranges at Lydd, then used for the firing of heavy ordnance. Only the guns of the Heavy Battery were sent initially. This exercise lasted two weeks during which period the farmhouses of Hirnant, Glanhirin and Troedrhiwdrain were evacuated.
By 1908 some of the guns firing on these ranges weighed up to five tons and fired shells weighing up to 280lbs over a distance of 5000 yards. The extreme limit of their range being 11,500 yards.
In August 1908 a number of officers from the School of Gunnery, Shoeburyness, arrived in Rhayader for an exhibition of firing with six inch howitzers. Shells of 280lb weight were fired and the flight of these could be followed from the gun muzzle until explosion. On the 5th of the month three batteries were in operation simultaneously firing with large 9.45 calibre guns, 120 rounds were fired at distances ranging from 2,500 to 5,000 yards.
At around this time the first artillery shoot orchestrated from an aeroplane was conducted here.
In 1910 a display of long range (6 miles) gun fire practice with star shells took place at night using 6'' and 9.45 '' calibre howitzers. During the day firing at a range of 9 miles took place using shells of 120 lbs for the 6'' guns and 280lbs for the 9.45 guns. It is possible to see the craters left by the shells on Esgair Cywion and Esgair Crawnllwyn. Shrapnel from these early firings can still be found.
After the declaration of war on 4th August 1914 the troops training on the Elan Valley hills were immediately withdrawn for embarkation to France.
After the war a memorial to the Special Constables from Birmingham who had guarded the treatment works from July 1917 till November 1918 was built after money was raised by subscription, and a water spout and drinking trough was built at Abernant, some 100yds above Caban Coch Dam.
World War 2
From the 2nd September 1939 an order from the Ministry of Transport prohibited the use of the Elan Valley road between Brick house and Pont ar Elan by vehicles of all types. Fulltime guards were placed at both ends of the Elan Valley and a system of passes was instituted for residents, tradesmen etc. The Foel tower was covered in netting, surrounded with barbed wire and steel doors placed over the entrance. An earth and stone blockhouse was also built near the tower. The Chalkhouse, by the filter beds, was also reinforced with large concrete blocks to form strong points.
By August 1939 plans were being made to block entirely the road at Brick House and Pont ar Elan, the roads to be closed one hour before sunset (not later than 8pm) until 8am. A guard acquainted with the inhabitants of the district was stationed at each gate during the time of closure to allow local traffic passage through. Watchers were also stationed at strategic points in the valley.
In September 1940 a splinter proof air raid shelter positioned on the hillside above the school was provided for the children attending the Elan Valley School.
As in WW1 the Elan Valley watershed was requisitioned by the military for battle training purposes and artillery practice. On the 16th July 1942 the tenants of Glanhirin, Nantybeddau and Claerwen were removed from their homestead with all their belongings in an agreement with the War Office Special Training Area Committee and the Birmingham Corporation. The farm tenants were instructed to complete their sheep shearing before the start of the military operations on 1st August 1942.
The Corporation was also concerned that an attempt to land aircraft on the reservoirs and attack the installations from the water might be attempted, and so a system of booms and rafts was constructed and placed on the Caban reservoir. Booms were also placed around the Foel tower. The vulnerable sluice valves at the base of the tower were buried in gravel and covered with a false concrete floor to prevent possible damage by any explosives, which might be dropped down the shaft.
In October 1940 motor launches provide by the Admiralty were placed on several of the reservoirs. Royal Navy personnel manned the launches with machine gun crews drawn from the local Home Guard. Slipways were constructed for the launching of the motor launches. This scheme was abandoned after 1 month when the launches were immobilised and armoured cars took over their duties.
An AA battery and two searchlights were situated on the Breconshire side near the Caban dam and another two AA batteries and searchlights on the Radnorshire side near Black Rock corner, both withdrawn in 1943. The concrete 'pillbox' in the Foel car park is still in situ.
In the early stages of dam construction in the Elan Valley a small masonry dam was built across the Nant y Gro stream, creating a 1,000,000 gallon reservoir on the rocky slopes upstream from Caban Coch providing water for the navvie's village. After completion of the dams the navvies' village was demolished and a new stone built village obtained water from the new scheme. However, Nant y Gro Dam remained intact, and provided a valuable test bed for experiments involving the military objective to breach a series of large dams in the Ruhr Valley, Germany, in order to disrupt the production of armaments in the industrial centre of the Ruhr below the dams.
In 1942 secret tests and experiments were carried out by the War Ministry involving Barnes Wallis, an aeronautical engineer at Nant y Gro Dam. The remoteness of the dam was an advantage for the top secret trials to be conducted without fear of being observed. A mine was suspended at the optimum depth from scaffolding halfway along the 180ft dam and detonated remotely. The success of this trial confirmed that it would be necessary to deliver an explosive device underwater and in direct contact with the wall in order to destroy the dam. These and other secret trials resulted in the 'bouncing bomb' being perfected by Barnes Wallace and the now famous raid by the '617 squadron'. Some remains of the dam at Nant y Gro are still evident today, and a walk to the site is possible from the Visitor Centre.Acknowledgement for much of this information to Brian Lawrence. Rhayader.