After losing the Sinai Peninsula 15 years ago in a humiliating military debacle, Egypt Sunday raises its flag once again over the entire mountainous and sandy wilderness whose strategic and emotional importance have become indelibly imprinted on the national psyche after four traumatic wars with Israel.

President Hosni Mubarak has ordered a simple flag-raising ceremony in Rafah in the north and Sharm el-Sheikh in the far south of the Sinai to mark the occasion. But he has decided not to give a speech or to attend either ceremony, reportedly for security reasons.

Instead, Mubarak will stay in Cairo and lay wreaths at the tomb of the unknown soldier and at the crypt of slain president Anwar Sadat.

Meanwhile, in a starkly simple parade of the few remaining Israeli troops in Sharm el-Sheikh, where the Red Sea and Gulf of Aqaba converge in the shadow of majestic granite mountains, an Israeli brigadier general will read the final order of the day and furl the blue-and-white Star of David flag as Israel takes its leave of the Sinai for the third time since the Jewish state was founded 34 years ago.

A dispute continued today over the alignment of the border at Taba, overlooking the Gulf of Aqaba near the Israeli city of Eilat, but it is not expected to affect the turnover.

Despite two weeks of frenzied negotiations and the involvement of U.S. Deputy Secretary of State Walter Stoessel as mediator, the two sides have not agreed where the border should run or whether to submit the dispute to international arbitration. It was not clear whether Israel would withdraw to the Egyptian or the Israeli version of the 1906 international boundary there.

Egyptian Foreign Minister Kamal Hassan Ali said at a press conference today that the whole issue was still under discussion and that there might be another last-minute meeting among Israeli, Egyptian and U.S. negotiators Sunday morning.

"On the Israeli withdrawal there are no difficulties whatsoever," Ali said. "The remaining issue of the border at Taba and other areas is still under discussion."

The absence of lavish celebrations to fete either the Sinai's return or the peace treaty with Israel that made it possible seems to reflect the ambiguity of Egyptian feelings toward the meaning of the event.

On the one hand, its symbolic importance to Egypt is enormous. It is not just the regaining of national sovereignty over a piece of land lost in war. It is also the restoration of national pride and the final washing away of the deeply felt shame inflicted on this ancient nation in the worst military defeat of its contemporary history.

The Sinai, once a distant land of no perceived national interest or value, is now held in special regard because of this. The Egyptian press is calling it the precious "eastern gate" to the Nile Valley heartland and the nation's "strategic depth" for its defense.

Today's ceremony is also a landmark in the tortuous search for a peaceful settlement to the Arab-Israeli conflict. It stands as an illustration to a highly skeptical world that lands lost in past wars with Israel may be regained through negotiations rather than fighting.

"It shows you can deal with Israel through diplomacy and not only with bullets," said Mustapha Amin, a leading Egyptian political commentator. "We got our rights back without a war."

But at the same time, the absence of fancy celebrations such as Sadat, the visionary and a chief architect of the peace treaty, envisaged for the occasion also reflects the Egyptian sensitivity to the circumstances in which the final Sinai ceremony is taking place.

For one thing, the restoration of Egyptian sovereignty with still no solution in sight to the Palestinian issue is a bitter reminder of the main criticism leveled against Sadat by his enraged Arab allies, namely that Egypt was making a "separate peace" with Israel only to get back its own territory.

Given the historic moment of the event, the Egyptian press has been surprisingly subdued in its coverage and commentary until almost the last minute. This was due partly to the uncertainty until almost the very last day about whether Israel really intended to go through with the return of the Sinai.

The whole nation has gone through a nerve-wracking exercise in collective breath-holding as its leaders engaged in feverish diplomatic activity to placate the Israelis over various last-minute demands, complaints and allegations of Egyptian violations on the peace treaty--all under the threat of a delay, or even cancellation, of the final pullout.

The effect was to dampen considerably Egyptian appreciation of the Israeli sacrifice and even to raise new doubts about dealing with Israel as a peace partner.

"All the last-minute problems have spoiled the meaning of the gesture," said Mohammed Salmawy, a top editor at the semiofficial Al Ahram newspaper. "The general feeling is that we have taken back the Sinai in spite of Israel. The sense of the grand gesture has been lost."

Furthermore, many Egyptians like Salmawy do not see the return of the Sinai resulting as much from Israeli generosity as from the perceived "victory" of Egypt over Israel in the 1973 Arab-Israeli war.

But there are other explanations for the moderation in public rejoicing as well. The principal one is the desire of Egyptian officials not to upset further the Israelis who are beset already by doubts about the wisdom of giving up the land because of uncertainty that the peace with Egypt will last.

Another is the high price many Egyptians feel their nation has already paid for the Sinai in agreeing to become the first Arab nation to make peace with Israel.

Part of the cost is calculated in Egypt's isolation from the rest of the Arab world and alienation even from the Nonaligned Movement Egypt helped found three decades ago. The suffering inflicted on Egyptian pride at no longer being the political center of the Arab world has been acute.

In addition, many Egyptians believe that the peace treaty with Israel was a primary cause of Sadat's assassination in October at the hands of Moslem extremists.

A third factor in the decision to play down celebrations is no doubt the desire to avoid being seen gloating over the recovery of Egyptian territory at a time when there are fears that Israel may make the Palestinians pay by invading southern Lebanon or annexing the West Bank.

Yet another reason is the still-simmering controversy at home regarding the conditions under which Egypt is taking back the Sinai. Many Egyptian critics of the peace treaty assail Sadat for surrendering a crucial element of Egyptian sovereignty by agreeing to a largely demilitarized peninsula under the supervision of an international peace-keeping force.

Four wars with Israel have given the Sinai a new meaning in the thinking of Egyptian intellectuals, policy makers and military planners. Before 1967, most Egyptians had never visited or shown the slightest interest in what was generally regarded as a barren wasteland inhabited by primitive Bedouins.

Today, the Sinai is the center of the government's attention and planning because of the region's crucial importance during the wars with Israel. Its development and the settlement of Egyptians there are regarded as urgent national priorities.

This new Egyptian outlook was reflected in the latest issue of the weekly magazine Mussawar, whose editor, Makram Mohammed Ahmed, wrote that had Egypt developed the Sinai, "the Israelis would not have been able to get to the east bank of the Suez Canal on that damned day in June" 1967.

"The crucial issue today," Ahmed wrote, "is that the Sinai should be in the conscience of every Egyptian now. The feeling that Sinai is still the gate of peril should be deepened within us because the peril always came through the eastern gate. We should realize that the population vacuum that has existed in Sinai so long left the land there open to aggression."

The loss of the Sinai in the 1967 war remains one of the most painful memories for Egyptians. The complete rout of Egypt's forces in just six days and the pell-mell flight of its troops and tanks before the lightning advance of Israeli armored columns was seen as a national disgrace and a shattering blow to Egyptian pride.

The reasons are still debated among Egyptian historians and politicians. Sadat blamed the then-defense minister Abdel Hakim Amer, who he charged had ordered the sudden withdrawal of the Egyptian Army without attempting to make a stand in the mountain passes.

As great as Egypt's shame was over the loss of the Sinai in 1967, so was the exhilaration over the Egyptian success in recrossing the Suez Canal during the first days of the 1973 war, storming Israeli defense lines and seizing back a small slice of the lost territory.

Although the Israelis rallied and countered with a brilliant military operation back across the canal to surround the entire Egyptian Third Army, Egyptians had already regained their national pride and dignity from the initial successes.

This accounts for the belief among many Egyptians today that they "won back" the Sinai on the battlefield.