Campaigners have started the fight to stop 423 homes being built on farmland in Fleet.
Berkeley has finally submitted a planning application for the homes on fields at Grove Farm and Netherhouse Copse, on the western side of the town.
It said the scheme was an ideal opportunity to help meet local housing needs and offered many community benefits, while also respecting the green gap between Fleet and Crookham Village.
But pressure group FACE IT (Fleet and Crookham Environment Is Threatened) fears the development will ruin an area of ancient woodland and is urging residents to object in the strongest possible terms.
“This plan will destroy precious countryside and add up to 423 new houses to our already over-stretched infrastructure,” warned Max Clark, vice-chairman of FACE IT.
“This is yet another bolt-on development to Fleet in a site that is not a suitable location for large-scale housing development.
"It is a greenfield site that forms part of the Hart Valley, which is an important ecological and landscape feature of the area and is an existing open space amenity for local people.
“Development here would cause environmental damage and will cause additional infrastructure issues with a road system already overburdened with significant other local developments.”
Mr Clark said it was important that local people made their views known on the application.
“Tell your friends and neighbours and encourage them to get involved,” he added.
“The more responses, the better chance we have of influencing the decision.
“Berkeley needs to know how local people feel about the threat to this area, which is an integral part of the Hart River Valley and crucial to the local environment and biodiversity.”
FACE IT said it was particularly important that Grove Farm, Pilcot Farm and Cross Farm wre maintained as a "green gap" to preserve the village identities of Crookham Village and Dogmersfield, and to prevent their coalescence with Fleet and Church Crookham.
The group pointed out that the valley of the River Hart was more biodiverse than some nearby designated areas, with important populations of some of England’s most threatened and iconic wildlife and habitats.
FACE IT also said there were already insufficient secondary school places in the area, while local roads are at capacity.
“The population of Fleet has increased by 9,000 in the last 10 years, but no new GP surgeries have been built to accommodate this significant increase in population,” said Mr Clark.
“Existing surgeries are already overloaded and need further investment.”
Berkeley, which has the option to buy the land from a private landowner, said its application was formed following public exhibitions in May.
Its plan includes providing green space and land for the extension of sports pitches at Calthorpe Park School.
There will also be children’s play facilities and land for a community building.
Berkeley said its proposal represented a "sustainable urban extension" to Fleet and made a "significant contribution" to the local authority’s housing needs.
It hopes construction can start next year assuming Hart District Council grants permission, with a decision date set for before October 2.