More than 15,000 police and soldiers took up positions in southern Israel on Tuesday to prevent the marchers from reaching Gaza - declared a closed military zone - and sabotaging the pullout scheduled to begin in two weeks.
Thousands of protesters - many of them teenagers and parents with small children - wearing orange shirts and ribbons, the colour of the protest movement, descended on an open field next to a sports centre in the middle of Sderot.
Posters lashing the pullout were plastered across the town.
Buses and cars caused traffic jams as they descended on Sderot. Over the stage hung a sign that said "Mass march to Gush Katif".
The march, scheduled to begin on Wednesday, is the settlers' second effort in two weeks to breech the barricades preventing them from getting into the Gush Katif settlement bloc in southern Gaza.
It was the same sign over the stage at a rally two weeks ago in the nearby town of Netivot.
"It is impossible to stop the masses of Israel who have only one goal, to reach Gush Katif and overturn this cruel decree"
Settler leader Avner Shimoni
Police and soldiers prevented those protesters from getting anywhere near Gaza, herding them into the small community of Kfar Maimon, where they stayed for three days in the blistering heat before dispersing.
If they fall short again, it would be a devastating blow to the protest movement.
"Our goal has been stated openly: To go Gush Katif, to our besieged brothers," Gaza settler leader Avner Shimoni told Channel 2 TV.
"It is impossible to stop the masses of Israel who have only one goal, to reach Gush Katif and overturn this cruel decree."
Police had originally said they would limit the crowd to 5000, but later estimated 10,000 people were at the rally, roughly half the number at the Netivot rally.
Border town tensions
After days of negotiating with the authorities, settler leaders were given permission to hold their rally on Tuesday in Sderot, an Israeli town that borders northern Gaza and has been the frequent target of rocket attacks by Palestinian fighters.
Israeli border police are preparing
for a difficult withdrawal
As the rally in Sderot ended, Palestinian fighters fired three homemade rockets towards Sderot, but two rockets misfired, landing in a Palestinian area, killing a three-year old boy and wounding nine other people, Palestinian rescue workers said.
The third rocket landed in an open field outside Sderot. There were no Israeli casualties.
A few minutes later, an explosion was heard outside the Gaza City house of a former Palestinian cabinet minister, witnesses said. No one was hurt, police said, but they kept reporters away. It was not known who set off the explosion.
Minister's home targeted
On Monday, a blast damaged a wall outside the home of the Palestinian Authority's attorney-general in Gaza City.
The two officials have been picked by the parliament to investigate widespread corruption in the Palestinian Authority.
Following the rally, the protesters planned to spend the night in Ofakim - an Israeli town about 30km from Gaza.
Police officials said they reached an agreement with settler leaders that would allow the protesters to stay in Ofakim until Friday, but some settler leaders said they would begin marching to Gush Katif on Wednesday.
The authorities said police and soldiers would form human chains and erect roadblocks throughout the area to stop the march.
Some of the protesters in Sderot said there was really no chance for them to stop the pullout.
"It seems that it is too late," said Alain Bismuth, 40, from the northern town of Haifa. He said he came simply to show that there are many Israelis opposed to the plan.
"It seems that it is too late"
Alain Bismuth, 40, Haifa resident
"Everything we do changes things"
Shmuel Lax, 30, of Neve Tsuf
Others still had hope. "Everything we do changes things," said Shmuel Lax, 30, of Neve Tsuf.
"We are going to be strong and God will help us and hear our prayers and our demonstrations," hardline lawmaker Benny Elon said.
Israel plans to pull out of all 21 Gaza Strip settlements and four out of 120 in the West Bank in mid-August, uprooting between 8000 and 9000 settlers.
The government says more than half of the settlers have agreed to leave voluntarily and expect more to follow before the withdrawal date.
But some settler leaders and their supporters plan fierce resistance. More than 200,000 settlers live in other parts of the West Bank, and their leaders fear the Gaza pullout could be the beginning of further withdrawals from land claimed by the Palestinians.
Despite the settler protests, Israeli military commanders will meet their Palestinian counterparts on Wednesday to continue efforts to coordinate the withdrawal, the Palestinian Interior Ministry said.