Firstly, commoners' rights were being eroded through army use, including the firing of live artillery shells, and piecemeal enclosure of land around the margins.

Many battles have been fought since, particularly against the military presence and the proposed building of reservoirs on the moor, notably under the Chairmanship of Lady Sayer, granddaughter of Robert Burnard.

For example, in June 2015, it supported the inhabitants of Widecombe-in-the-Moor against the erecting of a telecommunications mast in an area of pristine countryside against the wishes of the local population.

[6] Farming has continued through the medieval period to the present day,[7] but a more disruptive activity to the landscape was the appearance of tin-mining, firstly by stream-working, then by lode-working and finally by underground mining.

[16]: p.250–251  The taking of stone started to change the Dartmoor landscape: for example Eric Hemery (writing in 1983) stated that Swell Tor had been "decapitated and disembowelled by the quarrymen".

[17]: p.1029 In August 1881, a public meeting was convened by the Portreeve of Tavistock in the Guildhall to discuss the continued taking of stone, particularly from landmark tors.

In 1901, the DPA commissioned a report into damage to ancient monuments, caused by the taking of stone for building and road-mending, and into unlawful enclosures of common land.

[21] In 1963 the DPA published a widely circulated 24-page booklet entitled Misuse of a National Park which includes photographs of unexploded shells lying on the open moor, corrugated iron buildings, large craters, a derelict tank used as a target, bullet marks on standing stones, etc.

[1]: p.245  The Forestry Commission was founded in 1919, following World War I and in that year the Duchy of Cornwall planted 800 acres of conifers at Fernworthy.

[27] The DPA offered a viable alternative site, Gorhuish Valley, for various reasons, including the fact that minerals such as arsenic would leach into the water supply if Meldon were selected.

[1]: p.231 [32] The DPA learned in October 1951 that the BBC planned to build a 750-foot television mast on North Hessary Tor, near Princetown, that was erected in 1955.

[1]: p.238  When the decision was made to permit the mast, there were a number of conditions, included among them was that the development was built near the tor, leaving it still intact, and that its new approach road should not be fenced.

During the process of obtaining land for the transmitter, one MP asked in the House of Commons: "Will the Assistant Postmaster-General bear in mind that we have no desire to hinder the provision of this station but that it is felt that ancient common rights such as these, that have existed for a thousand years, should be adequately protected or properly extinguished by due process of law?

In 1956, permission was granted to rebuild the station as part of the "Gee" radio navigation system, to be occupied for ten years.

At a public enquiry in June 1973 Lady Sylvia Sayer represented the DPA and permission for development on the site was refused.

A few years later, DPA fought successfully in support of South West Water (SWW) against renewed calls for a new reservoir at Swincombe.

In March 1984, the DPA with other organisations petitioned Parliament opposing compulsory purchase orders on public open spaces.

[36] The Secretary of State announced in July 1985 that he was introducing a bill to reverse the decision of a Joint Parliamentary Committee and confirm a route through the National Park.

[45] The DPA argues that this is an activity that does not agree with the ethos of a National Park, whose purpose is to protect landscape from unsuitable development.

[46] The DPA revived its campaign with the publication of a booklet in 1999 when the Blackabrook Valley, Crownhill Down and Shaugh Moor, near the popular tourist area of Cadover Bridge, all came under threat from exploitation or dumping of waste.

[31] However, in November 2009, the clay companies, Sibelco and Imerys, produced a report reviewing old mineral permissions under the Environment Act 1995 with a view to joining up two pits.

The DPA were recorded twice, with other bodies, in a Devon County Council Development Management Committee Report for their representations in securing the future of the three areas where planning permissions were relinquished in 2001.

[51][52] The excavation in August 2011 on the north moor of a Bronze Age burial kistvaen, or cist, that was originally uncovered in 2001 was part-funded by the DPA, along with other bodies.

The old overhead line was readily visible from the B3212 Princetown to Yelverton Road, strung across Walkhampton Common from Devil's Elbow to just above Horseyeatt at Peek Hill.

The works to provide the new underground supply were mainly undertaken on the highway to minimise the impact on the sensitive moorland landscape, its archaeology, wildlife and livestock.

It also houses some typical Dartmoor archaeological features, such as a 4,000-year-old Bronze Age burial kistvaen (or cist) and a medieval granite cross from Ter Hill.

[57] The DPA were involved in a campaign in June 2015 against four telecommunications masts planned for Dartmoor, with the first to be erected in the village of Widecombe.

At short notice, the DPA banners were taken out, letters written, press interviews given and support given to the villagers when an inflatable mast was demonstrated – with the effect that the planning application was withdrawn.

The DPA has twenty-two policies listed on its web site: regarding access and rights of way, fencing, protecting monuments, diverse habitats, bracken, china clay quarrying, military training and live firing, hill farming and small scale traditional local industries, quarrying, television and telephone masts, wind farms, planning applications, housing developments, woodlands and forestry, ponies, swaling, and recreational activities.

[66] The DPA conservation team meet throughout the year to work on a number of ongoing projects; from gorse clearance, to habitat protection and archaeological surveying.