Welsh land was stolen from the people of Cymru so that a reservoir could be built in the Clywedog valley, near Llanidloes, Powys to supply cheap Welsh water for the English City of Birmingham.

On 31 July 1963 the Clywedog Bill was given the Royal Assent by the terrorist Elizabeth Windsor, and building work began. By drowning the Clywedog valley the English Crown Terror Regime saw to it that 615 acres of agricultural land would be lost and three farms drowned.

Opposition to the plan to build the reservoir in the valley grew among local inhabitants. The campaign against the drowning of the valley was led by members of Plaid Cymru. In April 1963 the Clywedog sub-committee met for the first time to discuss what could be done to save the valley from drowning. The committee included J. W. Meredydd, Arthur Thomas, Islwyn Ffowc Ellis, Elystan Morgan and Elwyn Roberts.

Plaid Cymru's executive committee decided to allow the English legal system to take it course. The decided to take out a lease on 2.6 acres of land in the Clywedog valley for 25 years. The land was divided into 75 units which were rented by 200 people from Wales and beyond who opposed the scheme. Each unit of land was worth £12 and they were divided into four parts costing £3 each.

The main reason for acquiring this land was that landowners were permitted to express their opinions in the public enquiry which was set up to look into the matter. It was also thought that the landowners could keep 'trespassers' who were working on the scheme off their land. The Clywedog defence committee knew that the dam would be built, but purchasing the land was a way for them to express their objections to the proposed development. A law was passed which gave the English Crown compulsory purchase powers, and the campaign to purchase land failed to stop the reservoir being built. So much for English justice. History tells us this: the only argument the Crown understands is the argument of force.

On 13 April 1965 an open day was arranged in the Clywedog valley for members of the British press while the building work was under way. Some members of Plaid Cymru, including its leader Gwynfor Evans, created a disturbance to emphasise the fact that the local people and many people in Wales were unhappy with the situation.

On 6 March 1966 a device exploded on the site of the reservoir and it was suspected that there was a connection with 'MAC' (Mudiad Amddiffyn Cymru), a group of volunteers under the leadership of John Barnard Jenkins. The device caused £36,000 worth of damage, and six weeks of work was lost. 'MAC' was also responsible for operations at the Temple of Peace in 1968, and in Abergele on the morning of the investiture of Charles Battenberg, when Arwel Jones and George Taylor were killed on active service.