The meeting was arranged after Barratt Homes entered into an agreement with the land owner of Seven Cornfields, Wolverhampton, to develop proposals for housing.
The green belt land has been put forward for review as part of the Black Country Plan, which is looking at new areas for homes in the region to address a shortage.
However the proposals have attracted strong opposition from residents who have raised concerns about the impact on local infrastructure and wildlife.
About 250 people packed into St. Bartholomew's Church in Penn last night to voice their opinions on the plans.
The meeting was also attended by a mix of Labour, Conservative and independent politicians with Wolverhampton South East MP Pat McFadden, Dudley North MP Ian Austin, Wolverhampton South West MP Eleanor Smith and South Staffordshire MP Gavin Williamson all at the church along with a number of councillors.
Mr McFadden said brownfield sites should be focused on for developments.
He said: “We have many many brownfield sites in Wolverhampton and across the Black Country. These sites could and should be used for new housing.
“The city should not be forced to choose between the new housing that we need and the green spaces that we love.”
Mr Austin added: “This is really precious open land between Sedgley, Wolverhampton and Staffordshire.
“When this is gone it’s gone forever and it would be a savage act of vandalism to lose it.”
'We're going to stay united'
More than 4,500 people have now signed a petition against the development.
Ms Smith added: “Housing companies like that don’t really care about us but we’re going to stay united.”
Tory councillor Sean Keasey, for Sedgley, said the extra traffic would "devastate" Sedgley.
He said: “It’s a nightmare driving through Sedgley at the best of times.
“16,000 residents and 8,000 cars is going to devastate Sedgley which is already putting up with other developments.”
Stuart Anderson, the prospective Conservative parliamentary candidate for Wolverhampton South West, got Prime Minister Boris Johnson to support the campaign to save the cornfields during a recent visit to London.
Mr Anderson said: “The developers are adamant they’re getting this through.
“They’ve invested hundreds of thousands of pounds and have been working on this for years.”
Schoolgirl speaks up
And a 13-year-old schoolgirl said she lives right next to the cornfields and walks her dog on it every morning.
“In school I’m on the eco committee and we’re trying to improve our school as the world is getting destroyed," she added.
One resident suggested fundraising to pay for potential barrister fees.
Around a third of the site sits on the Wolverhampton border, which is why the land has been included in the Black Country Plan.
However a large chunk of the land exists in the south Staffordshire district. This means that there are two different planning authorities for the 284-acre site.
South Staffordshire Council is also looking at new areas for housing. But it has not yet confirmed whether it is interested in the Seven Cornfields site.
An announcement is expected next summer.
Education Secretary Gavin Williamson said he would back the campaign.
He said: “The green belt helps to support our communities.
“I will be joining to support you and to ensure that what is so precious is something that we always fight to preserve.”