Passover, the celebration of the flight of the Israelites from Egypt three milleniums ago, was observed by Jews throughout Israel tonight with a bittersweet mixture of joyous reflection upon one historic exodus and deep national anguish over another.

The impending forcible evacuation of diehard settlers from the Sinai Peninsula--the dreaded "trauma of April" that has been on the mind of every Israeli ever since Israel decided to barter territory for peace--hung like a pall over a land so steeped in religious intensity that even prayer, at times, can be an expression of politics.

At the traditional Seder that marks the beginning of Passover week, the topic of the final exodus of Jewish settlers from Egyptian Sinai just 17 days from now inevitably filled awkward pauses in the reading of the Haggadah, the ancient enactment of the bondage of the Jews in Egypt and their tortuous journey through the Sinai's forbidding wastes to the promised land.

The elaborate, sing-song Seder ritual inevitably gave way to Talmudic debates comparing the exodus from the land of the Pharaohs with the exodus from Yamit, and whether the retreat from the idyllic Mediterranean resort town should be viewed as a dark chapter in modern Israel's short but tumultuous history, or merely a small episode in a long Jewish chronicle of searching for refuge and serenity.

In Yamit, opponents of the Egyptian-Israeli peace treaty, many of them nationalist settlers who arrived from the occupied West Bank, gathered for a final Passover feast and tried to put the best face possible on what most of them are beginning to accept as a lost cause.

It is certain now that soon after Passover week ends next Wednesday night, soldiers will move into Yamit and remove the last several hundred settlers opposing Israel's withdrawal from the Sinai, loading them onto buses and then closing the town for the April 25 turnover to the Egyptian Army.

Hundreds of Seder tables were set up in the sand dunes beneath the towering spirals of a war memorial to Israeli troops who died in the northern Sinai in the 1967 Six Day War. Scores of uniformed soldiers, assigned to guard some vacant Yamit houses to prevent militant settlers from occupying them, joined in the feast, breaking matzo and drinking wine with the same people they will have to remove forcibly in a few days.

A huge banner hung from one of the memorial's spires, declaring in Hebrew, "The blood of your brothers calls to you. Do not forsake our blood!"

On the nearby Sinai coast road, soldiers manning roadblocks for the night watch were issued Passover rations of gefilte fish, grape juice and matzo wafers with which to conduct the Seder as they monitored the influx of arriving settlers.

But despite the festive atmosphere of the settlers' Seder, and the joyous singing of "Hevenu shalom aleychem" ("We've brought peace"), the dream of Yamit had turned into a nightmare for many of its founders.

They had dreamed of building a Shangri-La, a Jewish oasis in the parched desert sand, painstakingly cultivating and watering the dunes until they were abundant and green. They called themselves pioneers, and, inspired by the best instincts of the pioneering tradition, they were united in their cause.

In the end, however, they were piteously divided, fighting among themselves over generous property compensation offered by the state, and derided by a once-admiring nation as money-grubbing land speculators trying to enrich themselves at the public's expense.

All but a handful of them have left, and most of their neat, white stucco homes have been taken over by squatters who never lifted a shovel in Yamit, or patiently nurtured a tiny plant until it grew into a tree in a struggle against alien elements. Yamit now looks like a cross between a refugee camp and a battle zone, defaced by vandals and scavengers and fortified by zealots.

The walls of the neat white bungalows are smeared with spray-painted slogans condemning the price Israel paid for peace and hinting ominously at Jewish civil war. Sandbag bunkers, ringed with coils of barbed wire, have been erected on some roofs, manned by tough-looking young sentries threateningly holding iron pipes and other makeshift weapons.

Bomb shelters have been converted into redoubts by militants of Rabbi Meir Kahane's Kach (Thus) movement, an offshoot of the Jewish Defense League, and teen-age zealots just arrived from the United States shout out from behind their locked doors that they are prepared to die defending Yamit against the invading Israeli soldiers. There is even dissension among these temporary inheritors of the shell that once was Yamit.

"Why do you talk to those crazies? They are lunatics," an orthodox Jew, an activist in the Stop the Sinai Withdrawal movement said when confronting a reporter last week. The protester said he would offer only passive resistance to the soldiers when the evacuation begins.

But Israel is a diverse society, and although the focus of much of the nation is on Yamit this Passover week, with its symbolism of the "new exodus," thousands of secular Jews turned the occasion into nothing more than a beach holiday. Others crowded Ben-Gurion International Airport, fleeing on vacations to the Greek islands and Europe, as if anxious to forget the April 25 trauma.

And in Cairo, far from the turmoil of Israel's debate over the retreat from the Sinai, a dwindling community of about 400 mostly elderly Egyptian Jews celebrated the departure of the children of Israel more than 3,000 years ago, ending with the traditional prayer, "Lashana haba'abi y'rushalyim!" ("Next year in Jerusalem!").