Officers in charge of a multi-million pound policing operation have pledged to protect the interests of all sides as the clearance of Dale Farm travellers' site gets under way.
Essex Police intelligence suggests that up to 2,000 supporters from 30 different groups will swell numbers on the six-acre plot near Basildon.
Police numbers will be bolstered as riot-trained officers are drafted in from forces including the Metropolitan Police, Thames Valley, Norfolk and Suffolk.
Assistant Chief Constable Sue Harrison said the precise cost of the policing operation will not be known until it is complete.
The British Home Office has announced it will pay up to £4.65m or half of the total bill.
Fifty-one homes - housing and estimated 400 people - are to be cleared on the illegal side of the site. About 50 legal homes will remain.
Supporters and travellers insist they will offer non-violent resistance despite reports they are preparing to "wage war" against the authorities.
They deny that gas canisters have been hoarded as weapons and that they are preparing to pelt bailiffs with bricks.
Instead they say they will form obstructions either using barricades or by large numbers of people occupying space.
Chief Superintendent Tim Stokes is leading Operation Cabinet, the name given to the force's response to the Basildon Council-led evictions.
He said: "A successful result for us would be if we didn't have to step foot on the site at all.
"This is a Basildon Council operation and our role is to protect everybody involved and to prevent crimes and breaches of the peace.
"Mistakes have been made by police forces in the past but we are absolutely clear that our role is to prevent bailiffs breaking the law as much as it is to prevent supporters and travellers acting illegally."
The force has been monitoring the site as well as tracking the activities of supporters through social networking.
They expect to find protesters keeping a 24-hour sentry on the gantry at the site's gateway as well as barbed wire and concrete filled barrels which supporters can handcuff themselves to.
Mr Stokes said: "We have to be prepared for the worst case scenario. We could face violent disorder, a drawn out stand-off or peaceful and passive resistance.
"We believe there will be people on the site who are intent on violence and we must police them rigorously and robustly.
"There are travellers on the site who value the presence of the supporters but there are also some who are fearful of them.
"We need to be aware of that dynamic and respond to the different challenges that presents."
He added that the force has sought to meet with all groups in the build up to the clearance.
As well as talking to bailiffs, the force has met with travellers to discuss mistakes made during previous evictions.
He added: "We are pledging to maintain our response and safer neighbourhood policing levels across Essex throughout this operation.
"It is a multi-million pound operation but, if there is no trouble, it is an operation we can scale down very rapidly."