It will begin shortly after dawn on Wednesday when the first squad of 16 unarmed soldiers and police - men and women - arrive at a front door somewhere in Gaza and ask the settlers to leave, or be taken away by force.

Some 6,800 security forces will go door-to-door to carry out the evacuation process, divided into 400 teams.

They will be the sharp end of a huge military operation numbering upwards of 40,000 troops - including 35,000 supporting them in six circles radiating outward from the settlement being cleared that day.

"First we are going to take all the people out. Then we are going to evacuate their equipment from their homes. Then we are going to dismantle any infrastructure that we are ordered to," said one senior Israeli commander.

"Then we are going to take all the military infrastructure out, then we are going to deploy outside the Gaza Strip."

The latter stages are straightforward - bring in private furniture removers to haul away the detritus left behind by settlers who insisted on staying, and use industrial contractors to de-toxify, demolish and remove the 65,000 lorry-loads of rubble.

It is the first stage that will prove the hardest - dealing with emotional settlers long accustomed to an army that defended them, or at worst turned a blind eye to their activities establishing new outposts in the West Bank and Gaza.

Israeli planners expect half of Gaza's 1,600 families to remain, reinforced by up to 5,000 West Bank and other radicals who have infiltrated over the past few weeks to join their resistance campaign.

"It's going to be, if not the most sensitive, maybe one of the most sensitive challenges we have had to carry out in terms of not having consensus within Israeli society," said one senior military official.

Determined not to turn weapons on their own people Israeli planners have resorted to sheer force of numbers to overcome the usual benefit of arms.

"The deployment has to be five times the number involved in order to ensure minimum casualties so that when you use physical force you don't have to use lethal weapons," said Ranaan Gissin, a senior adviser to the Prime Minister, Ariel Sharon.

To this end the inner evacuation teams will form an inner circle, unarmed but supported by snipers and armed backup teams if a settler loses his head and starts firing. A second circle will isolate the evacuated settlement from other settlements, to stop neighbours charging in to provide reinforcements.

A third will isolate other settlements and Palestinian towns nearby, with a fourth - much more heavily armed - ready to punch into the Palestinian areas and bring heavy weaponry to bear if Palestinian militants open fire during the pullout.

Few expect the Israeli Government to show any mercy if Hamas or Islamic Jihad decide to fire a barrage of rockets at the departing Israeli troops. "If they choose fire, we will respond with fire, more severe than ever," Mr Sharon warned in his televised address to the nation.

A fifth circle of security will be set up around the Green Line, along the electronic and heavily fortified fence separating Israel from Gaza, and the sixth circle of roadblocks and checkpoints within Israel itself to ensure no demonstrators approach Gaza.

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