Two protesters chained themselves to a barrel behind the gate at Dale Farm today to signal the start of peaceful resistance.
Dean, 29, and Emma, 18, handcuffed themselves to a pole concreted inside the barrel as a human barricade.
Lying on mattresses, the pair said they were prepared to stay as "long as it takes".
Dean said: "I have studied what's going on here long and hard and believe when the law is used for wrong, civil disobedience is the only way to oppose it.
"The idea is the bailiffs cannot open this gate without killing us both. We'll sleep here for weeks if we have to."
The clearance of 51 unauthorised plots, home to up to 400 people, on the six-acre site in Essex is due to start this morning following a decade-long planning row.
An estimated 200 supporters and residents remain on site.
More protesters have chained themselves to obstacles inside the site.
One, Ruth, has attached herself to a car. She said: "There are people here from all over the world and the travellers have made us so welcome.
"It has become increasingly difficult for travellers to find a site in recent years. Planning law is very discretionary and we do not feel it's being used fairly."
One of the leading supporters, Grattan Puxon, said: "The gate is closed but talks with the council are going on behind the scenes. The council owes us 62 pitches for those who will be made homeless.
"We have a High Court hearing at 11am so there is still hope this will pass quietly."
Resident Kathleen McCarthy said the travellers feared it was inevitable that they would be forced to leave.
She added: "If they had any human decency this could be stopped, I plead and beg to stop this.
"Look what these people (the protesters) are doing to save us."
Paintings of children and a banner calling for "Human rights for Dale Farm" had been attached to the outside of the main barricade.
There was also a sign warning about the protesters chained to a barrel, which stated: "Danger of death. Behind this gate a woman is attached by her neck. If you attempt to open this gate you will kill her."
The travellers also built a small wall at the end of a road connecting the bailiffs' compound with the site.
Supporters inside the site said their demand to Basildon Council is to provide 62 plots to temporarily house those made homeless while planning permission is sought for other sites.
They said the council has asked for a small legal wall blocking the bailiffs' way to be removed and for two bailiffs to be allowed to look inside the site.
Liberal Democrat MP Andrew George, the chairman of the all-party parliamentary group on travellers, said that the Dale Farm eviction should be put on hold.
Mr George told Sky News: "The Government and the local authority are going to be spending up to about £18 million to restore the site to what it originally was, presumably - and that is a scrapyard. It's going to make it the most expensive scrapyard in history.
"I think that both to save money and to be more humane and also to ensure that the people living on this site are given a genuine opportunity to find somewhere else to live or even to regularise the arrangements on that site, they need to be given time rather than sadly - and I think very inappropriately - to be going ahead with the evictions today.
"Simply to make people homeless and to tell them to move onto some other site, when they know full well there are no other alternative sites, is just telling people to move from one illegal situation to another."
Resident Kathleen McCarthy, Yvonne MacNamara from the Irish Traveller Movement, and Joe Jones and Richard Sheridan from the Gypsy Council are due to meet council delegates outside the gate for discussions after 10am.
John Baron, Conservative MP for Basildon and Billericay, said: "I'm hoping for a peaceful solution to this and a peaceful site clearance.
"I think we are going to see a fair bit of negotiation in order to achieve that. But at the end of the day this is a site clearance."
Mr Baron added that the clearance would not be rushed.
"We have always had moral right on our side in this argument, and I want us to maintain that moral right, right through to the end.
"This site will be cleared, but I don't want to sacrifice moral right for speed," he said.
The arguments behind the dispute at the former scrapyard – human rights and unauthorised planning permission on 51 plots at the centre of them – appeared lost last night. A spokeswoman from the Dale Farm Solidarity Campaign said many residents had temporarily moved caravans on to the neighbouring legal site and human rights observers were present to witness the events as they unfolded.
"The only travellers now left are the ones that have nowhere to go," she said, speaking from the site, dubbed Camp Constant. One consolation, she said, was the media spotlight on the farm, which had helped to further the debate over the plight of the travelling communities.
That was of little comfort to Kathryn Flynn, a mother-of-three and a resident at Dale Farm for 10 years. "I'm moving on to my uncle's yard on the other side for tonight because I don't want my children to go through this," she said. "I'm scared of what the bailiffs will do. They smash up our trailers – our homes. I don't want my children to be in danger. Our children went to school for the last day on Friday.
"I don't know what to tell them about tomorrow. But we've got nowhere to go after Monday. We don't know what's going to happen to us."
Mother-of-four Michelle Sheridan, 34, said that she would be keeping her children with her, adding that many of the site's residents were single women and elderly people.
She said: "People here are scared and terrified. I have nowhere to go and I don't know what I'm going to do. I am here with my children and they will be with me. I'm their sole carer, that's my job. The bailiffs will have to come and take me forcibly."
Last night, in the absence of any more dramatic twists in the drama, such an outcome seemed inevitable.