Thousands of extreme Israeli ultranationalists rallied against the partial withdrawal from the Palestinian territories in two weeks time.
The demonstration in Sderot, an Israeli town that has been a target of Palestinian rocket attacks, could be a final show of resolve before a withdrawal, just two weeks away, which the protesters claim is a betrayal of Jewish claims on biblical land.
"All of the land is ours," read one banner amid a crowd comprised almost entirely of religious Jews dressed in orange, the colour adopted by opponents of the first uprooting of Israeli settlements from land Palestinians want for a state.
Under Prime Minister Ariel Sharon's plan to "disengage" from Gaza, a narrow strip of occupied territory he says Israel has no chance of keeping in any future peace deal, security forces are to begin evacuating 21 settlements on August 17.
Settler leaders said thousands of protesters at the Sderot rally would march to the Gaza frontier on Wednesday after spending Tuesday night out of Palestinian rocket range in another Israeli town, Ofakim, 20 km from the border.
"Tomorrow night we will resume the march, to Gush Katif," settler leader Zviki Bar-Hai said, referring to a bloc of settlements in Gaza. "We will do so with determination, but non-violently."
Security officials said a buffer force of 15,000 police and soldiers was in place to challenge any attempt to enter Gaza.
"We won't allow them into Gush Katif," local police commander Effi Mor told reporters.
The government at first banned the Sderot rally. Officials cited a risk of Palestinian attack or that protesters could slip past an army blockade on Gaza and reinforce settlers who have sworn to resist evacuation.
Relenting after late-night talks with the YESHA Council of Jewish Settlements, the government said a small-scale rally could go ahead on the understanding protesters would continue from Sderot to Ofakim, and then disperse.
Public Security Minister Gideon Ezra voiced hope that the YESHA Council that organised the rally would back down, as it did last month after police foiled a similar march on Gaza by penning in protesters for three days in a desert encampment.
Polls show that a narrow majority of Israelis support the Gaza pullout and plan to evacuate four of 120 Jewish settlements in the occupied West Bank.
"We are fighting for the soul of the Jewish people," said Adi Mintz, a YESHA leader.
Palestinians welcome any withdrawal from land captured in the 1967 Middle East war, but fear the Gaza plan is a ruse to strengthen Israel's hold on the West Bank.
The pullout affects 9,000 settlers, fewer than 4 percent of the 240,000 who live alongside 3.8 million Palestinians.
The World Court has branded all settlements illegal. Israel disputes this. The United States has said Israel could expect to keep some settlements under any eventual peace deal.