Local campaigners have launched a petition in a bid to stop the Ministry of Defence from de-registering a vast area of land in Cumbria.
The commons are to the north-east of Appleby-in-Westmorland, in the North Pennines Area of Outstanding Natural Beauty.
The Fells in question, Murton Fell CL76, Hilton Fell CL27 and Burton and Warcop Fell CL122, form part of the Warcop Ministry of Defence (MoD) training area.
And if the land is de-registered, campaigners say it will bring an end to "hundreds of years of tradition" within the farming community.
"When the MoD negotiated the buy-out and extinguishment of the commoner's grazing rights, one of the fundamental issues was MoD's agreement to leave the fells on the commons register," said William Patterson of the Hilton Commoners' Association.
"On the strength of this undertaking, the commoners' accepted the buy-out.
He added: "It is a breach of trust that the MoD now wants to cancel that undertaking without making a further agreement. I believe that to safeguard the future of these fells the land must remain on the commons register."
'Biggest land grab'
A petition has now been launched by Hilton Commoners Secretary, John McDarren, who hopes to gather 10,000 signatures before the petition deadline on 5 April 2019.
The petition says the MoD is undertaking the "biggest land grab since the 1800s"
The petition says: "Despite an undertaking by the Secretary of State, made after a public enquiry in 2001, that the fells would remain on the Commons Register in perpetuity.
"In 2003 the MOD purchased the grazing rights from the commoners. Part of the agreement reached was that the fells would remain on the Commons Register.
It adds: "Now they have cancelled that part of the agreement. Our argument is that it is not legally possible to cancel part of a multiparty agreement, without the other parties consenting, which they do not."
Common land is land subject to rights of common, to graze animals or collect wood for instance, or waste land of the manor not subject to rights.
