On Aug. 19, 1978, one of the most tragic theater fires of the 20th century took place in Abadan, a city in the heart of the rich oil-producing region of western Iran, now the object of attack and counterattack in the war with Iraq.

With the doors locked from the outside and firefighting equipment slow to arrive, nearly 500 people were killed, burned to death, suffocated or trampled.

The Iranian government charged that the fire was caused by arson, set by Islamic fanatics who were opposed to liberalized rules that allowed theaters to stay open longer than in the past.

But the opposition claimed that while the film was being shown, several anti-shah activists had run inside seeking to elude agents of SAVAK, the Iranian secret police. They charged that the agents, after securing the shah's personal permission, had locked the doors and burned the movie house down.

In 1978, opponents of the shah did not need proof to hold him responsible for the most terrible of deeds. Soon after the fire, his regime's culpability for it was taken almost for granted. The terrible disaster further united the many disparate groups in Iran who wanted the shah out of power.

At about the same time, the important in-baskets in Washington had yet another draft of the CIA's National Intelligence Estimate on Iran. Entitled "Iran: Prospect Through 1985," the report declared: "Iran is not in a revolutionary or even 'pre-revolutionary' situation."

At the State Department, an intelligence analyst on Iran, George Griffin, wrote a dissenting footnote to the draft. While the CIA estimate agreed with the conclusions drawn by Ambassador William Sullivan, the embassy staff in Tehran and the State Department leadership, to Griffin it seemed simplistic and wrong. Not only had press reports been painting a different picture of life in Iran, but embassy cables and intelligence reports since June had cited a growing alliance between the Islamic traditionalists and the other, growing dissident segments of Iranian society.

Griffin consulted an old hand on Iran, Kermit Roosevelt, the CIA agent who had coordinated the U.S. participation in the 1953 "coup" that kept the Pahlevi dynasty in power. Roosevelt told Griffin that the shah was, in fact, a weak man, a "defective personality," who would fold under pressure in a "failure of will."

Faced with disagreement, the CIA analyst in charge of the draft withdrew it from circulation. The issues would be reexamined again later. The Opposition

What most of these opposition groups in Iran shared were two goals: the removal of the shah from power and an end to what they perceived as foreign domination of Iran. It was perhaps the failure of American analysts to recognize the extent of the second of those goals that led to so great a misunderstanding of what Iran would be like after the shah was toppled.

Chief among the shah's opponents, of course, was the Ayatollah Ruhollah Khomeini. Sent into exile in 1963, Khomeini was living in Iraq, in the city of Najaf, the home of the most sacred Shiite Moslem shrine. Khomeini is now regarded by many in the West as leading Iran back into a religious dark age, but in 1978 he used the most modern of technological devices -- the tape cassette -- to smuggle his message of revolution back into Iran.

Constantly railing against the shah and urging Iranians to rid themselves of foreign influence, Khomeini's taped diatribes in the closing months of the year could be heard in nearly every mosque in the country. By the time of the Rex Cinema fire, Khomeini was the recognized symbol of resistance.

The theater fire in Abadan seemed not only to unite dissident groups in Iran but to have a deep, unnerving effect on the shah as well. Sullivan had just returned from Washington where he had lobbied on behalf of the shah's pared-down "wish list" of $10 billion in U.S. military hardware. To Sullivan, the shah suddenly seemed filled with self-doubt, a man who believed that nothing could work, who was no longer able to analyze events. The shah, according to Sullivan's reports to the State Department in Washington, was becoming unhinged.

According to one report, the shah told Sullivan that he had tried to suppress dissent with repression and that hadn't worked; he had tried to put in place a civilian government and that hadn't worked either.

Bitterly, the shah asked whether he should appoint a corrupt civilian government that would turn the populace against it and make it clamor for a more authoritiarian military government with himself back in full command. "I have to demonstrate the bankruptcy of the moderate option," the shah told Sullivan, "so people will see that a government is necessary to prevent chaos."

Jarred by uncertainty, the shah asked Sullivan what the United States government wanted him to do, and Sullivan passed the question on to Washington.

On Sept. 4, the largest demonstrations yet broke out across Iran. Three days later, the shah declared martial law in Tehran and 11 other cities.

On Sept. 8, Black Friday as it came to be called, the shah's troops fired into a crowd of demonstrators at Jaleh Square in Tehran. By the government's account, 86 people were killed; the opposition put the toll at more than a thousand. The demonstrators had not learned of the newly imposed curfew.

Jimmy Carter got news of the Jaleh Square massacre at Camp David, where he, Anwar Sadat and Menachem Begin had begun meeting to negotiate a peace between Egypt and Israel.

Carter was briefed on the incident by Harold Saunders, assistant secretary of state for the region. Secretary of State Cyrus R. Vance, according to a number of department sources, knew few of the details because he was nearly totally absorbed in the Egyptian-Israeli discussions and in nuclear arms limitation talks with the Soviet Union.

According to accounts of Saunders' briefing for Carter, the shah was still firmly in control of Iran. The skepticism that was beginning to spread among low-level State Department aides had not worked its way up. When Saunders finished, the president's national security adviser, Zbigniew Brzezinski, joined the briefing and declared that the shah needed a strong statement of U.S. support -- it would boost his morale and that of allies in the region. Sadat had already called the shah to pledge his support and suggested that Carter do likewise. The president agreed.

American policymakers viewed the shah's willingness to use force as a good sign. Sullivan noted that the declaration of martial law was an indication of renewed self-confidence on the part of the shah, and predicted that, despite reports of morale problems in the army, the shah and his military could handle the situation.

The Pentagon agreed, with its Defense Intelligence Agency issuing a report at the time that said the shah is "expected to remain actively in power over the next 10 years."

Unrest mounted in Iran during the rest of September and into early October. Faced with the new violence in Tehran, the CIA's National Intelligence Estimate was quietly laid aside. Viewpoints would have to be reconsidered. The State Department would redraft it.

The shah appointed a new, more moderate prime minister and decided to take action against Khomeini by formally asking the government of Iraq to expel him, to move him further from Iran. Agreement came quickly; Khomeini had been stirring up Shiite Moslems in Iraq as well.

Immediately, however, the shah took back his request. As dangerous as Khomeini was in Iraq, he might prove to be more dangerous in a European capital where he could get world press attention and maintain even better communication with Iran through more modern, long-distance telephone connections.

In early October the aging ayatollah, denied admission to Kuwait and Syria, went to France, taking up residence in a suburb of Paris.

The shah renewed his attempts to defuse turmoil and divide the moderate opposition from the radical Shiites through reform, promising amnesty for 1,500 prisoners. But on Oct. 24, virtually every city in the nation was hit by massive outpourings of protest, calling for the ouster of the shah or the return of Khomeini.

Sullivan, only recently so optimistic about the shah, once again feared that events were getting beyond control. In October, a small Pentagon group, led by Deputy Secretary Charles W. Duncan Jr. (now secretary of energy), met in Tehran with the shah and his military leaders and was informed that Iran was now willing to scale down its arms request -- "postpone," not "cancel" -- because it would be unable to pay for it all. Sullivan told Duncan that the shah was in dire straits but still might act decisively to resolve his problems.

The Pentagon group had just left Saudi Arabia where the royal family was deeply concerned about what it perceived as a failure by the United States to support its allies in the Persian Gulf.

The Saudis believed that the Soviet Union was sure to capitalize on chaos in the region unless the United States would make a show of strength. What the Saudis wanted, it was clear, was U.S. military intervention on behalf of the shah.

The Saudis' concern seemed exaggerated and their requests -- for U.S. assistance with covert subversion in South Yemen -- reckless. But as an absolutely vital ally, the Saudi perception of U.S. assistance was as important as the reality of it.

The shah's problems were internal, however -- and did not fit the Carter administration's criteria for direct intervention, since there was no real threat from outside.

Iranian generals began talk of taking matters into their own hands on behalf of the shah. Some wanted to "round up 10 mullahs and shoot them," one of Sullivan's aides said at a staff meeting, and 300 army officers had petitioned their leaders for permission to crack down on demonstrators.

Gen. Manuchehr Khosrowdad, the commander of Iran's air force, wanted to clear the streets once and for all. If intimidation didn't work, then mass arrests and bloodshed would.

When Sullivan and British Ambassador Anthony Parsons went to call on the shah, they found the shah unnerved once again, incapable of action, unwilling to make decisions, ravaged by the deaths in the streets.

Less the arrogant emperor and more like a befuddled bureaucrat, the shah pleaded for advice. Who should he appoint to what positions? Should he install a military government? Should he allow the military to use force, should he crack down? More and more "crack down" came into play in conversation.

The shah told Sullivan and Parsons that his ambassador to the United States, Ardeshir Zahedi, was urging him to take a hard line, to crack down as the troops had done the month before at Jaleh Square. According to the shah, Zahedi had come to Tehran with the word of Brzezinski that the Carter administration would support every action necessary to preserve order in Iran. aBut where was the direct U.S. support that was due him, the shah wanted to know.

The shah told Sullivan to ignore Zahedi. He was, the shah said, trying to relive the dreams of his father, a key figure in keeping the shah on the throne in 1953. The shah was uncertain about what to do, but he had come to a decision about what he would not do. There would be no "crackdown." If he killed thousands of his countrymen, he would have to rule by force for the rest of life and would be unable to pass the throne on to his son.

According to some accounts, it was at this point that Sullivan and the United States first learned that the shah had cancer. By then, Sullivan already knew that the shah believed he had no more than a few years to live.

Violence continued to grow. In Amol, near the Caspian Sea, dissident student groups took control of the city. For the first time, the shah's families and friends spoke of a revolution in progress.

In Tehran, 10,000 students at the university marched in protest; in the south 30,000 oil field workers walked off their jobs.

The shah continued to offer concessions. He dismissed 34 senior SAVAK officials who had been accused of torture and other abuses. At what was said to be Sullivan' suggestion, he agreed to grant amnesty to the political prisoners on his birthday, Oct. 26. He said there would be no future political arrests.

"Feeding the crocodiles," Sullivan called it, unconvinced that the shah's reform gestures, which transferred no real power, were sufficient to quiet the opposition. Sullivan concluded that the shah's new prime minister, Sharif-Emani was doomed and once more the shah would turn to him for advice.

The shah was under pressure from home to get tougher, to appoint a military government and turn it loose on the opposition. Gen. Hossein Rabii, who feared most of all the threat of communist subversion, complained to an embassy official: "His majesty is simply not being himself.He has got to assert himself or we'll make him assert himself."

By the the end of October, the news coming out of Iran had begun to divide the Carter administration. One viewpoint, shared by desk officers throughout the government familiar with daily events in Iran, maintained that the shah could not survive. The other camp, most forcefully represented by Brzezinski at the White House, believed the shah could stay in power and that the United States must make every attempt to keep him in power.

But Sullivan was concluding that the shah could no longer guide events as the all-powerful ruler. Leaving the Iranian military to its own instincts, he feared, would mean chaos -- either bloody repression or mutinous troops. When Sullivan cabled the State Department asking for advice, he made two suggestions: Urge the shah to begin to truly accommodate his moderate opposition by allowing the creation of a real parliament and prime minister, retaining for himself only foreign policy and the military. And suggest that the shah leave the country for at least long enough to allow the new administration to restore order.

Sullivan's request for instructions were urgent. He talked directly with David Newsom, undersecretary for political affairs and the No. 3 man at State, who was typically passive. Newsom told Sullivan of the difficulties of getting instructions cleared through the White House and Brzezinski.

But Vance and some of his aides were struck by the picture Sullivan had painted. Sullivan was on the scene; his views should be considered.

On Oct. 27, when Iranian experts from all departments met at State for an all-day session, the consensus of Farsi-speaking analysts was that neither more liberalization, which Persians would perceive as weakness, nor repression, would save the shah. Someone suggested a straw poll. Of 30 or 40 people there, only four believed that the shah would be on his throne a year later.

Aides to Vance met with Brzezinski's Iran specialist, Navy Capt. Gary Sick, to respond to Sullivan's request for advice. Sick said that Brzezinski wanted stronger language making it clear that the shah should not capitulate in any way to his opposition. Nevertheless, Brzezinski, through Sick, agreed on sending Sullivan a cable suggesting that the shah should be encouraged to relinquish some of his domestic authority and leave on vacation.

It seemed, for the moment, to be a major shift in U.S. policy, albeit a secret one. But it lasted only for a moment. The Pressure

On the day that cable was sent, the president received the shah's son, Crown Prince Reza Shah, at the White House. The young Iranian was a student at the U.S. Air Force Academy, and it was his 18th birthday. He was accompanied by Zahedi, now back in Washington.

"Our friendship and our alliance with Iran is one of our important bases on which our entire foreign policy depends," the president said in a public statement during the meeting.

Zahedi, who had learned that new secret instructions were on their way to the U.S. ambassador in Iran, was already busy trying to regain lost ground for the shah with a new expression of support from Carter. He got in touch with Brzezinski to complain. He warned other powerful American friends of the shah as well, including David Rockefeller, Henry Kissinger and John J. McCloy.

Rockefeller and Kissinger began calling contacts in the press and on Capitol Hill to bring pressure on the administration, warning that an Iran without the shah would rapidly turn communist.

McCloy went further than that. The former high commissioner to Germany after World War II, former president of the World Bank and chairman of the Chase Manhattan Bank, McCloy, at 83 years of age, was a partner in the law firm that represented the shah, Milbank, Tweed, Hadley & McCloy, one of the most prestigious law firms in the United States.

In letters and phone calls, McCloy urged Vance to support the most hardline aid for the shah, and to make it known that such support was coming. According to one State Department source, McCloy made it clear to Vance that he had also been in touch with the president.

According to one source with access to intelligence information, Zahedi opened another line of pressure, less subtle, to force a stronger endorsement from the president. Zahedi arranged for someone to contact Barbara Walters of ABC News and reveal Sullivan's new doubts about the shah and that U.S. support seemed to be declining. When Walters called Zahedi on the story, he at first seemed reluctant to talk -- then depicted the shah as debilitated by his lack of U.S. support. Sullivan was portrayed as taking a "go easy" line, meeting behind the shah's back with the opposition. The report warned of a communist takeover, in which oil supplies might be lost, U.S. arms might fall into the "wrong hands."

"Without the belief that Jimmy Carter will support him, the shah sits and waits," Walters reported on the evening of Nov. 2, which, it turns out, was one of the most accurate news accounts during this period.

The White House issued a denial. The president was not abandoning the shah. This is part of what Zahedi wanted to happen. The other part was a private communication from the White House, guaranteeing that Washington would not get cold feet if the shah embarked on military action to take over the oil fields and break up demonstrations. Zahedi wanted the shah to know, with certainty, that the United States would not shrink away if the TV news began showing American-made tanks rolling against Iranian citizens.

In fact, the president had not yet made up his mind about how far to go in supporting the shah or deserting him. He was not sure whether Sullivan's analysis made sense. And Brzezinski was offering an alternative view of the revolution in Iran, one which ultimately persuaded Carter to stand by the shah -- to the very end.

With a background as a lifelong academic before joining the Carter administration, Brzezinski mustered serious intellectual arguments in behalf of his position. Revolutions are not won by the will or might of revolutionaries, Brzezinski maintained. Instead, they succeed because of the absence of an effective authority in control.

Brzezinski had copied and gave to Carter a few pages by historian Crane Brinton, who argues that successful revolutions are marked commonly by the ineptitude of the government's use of force rather than the skillful use of force by the opposition. While a majority of the populace may be unhappy and wish the existing government overthrown, only a minority takes part in the actual clash of forces. The government that is overthrown is one which does not exercise tight control over its troops, which has military commanders of little intelligence, which losses its troops to the opposition.

Brinton went even further. People are generally so conservative, routine-loving and obedient that virtually no government is likely to be overthrown from within until it loses its ability to use its police and military powers against the small cadres who make revolution.

In addition to this argument, Brzezinski added the weight of reports on Iran coming in from elsewhere in the government. Some in the State Department now wanted to ease the shah out of power, Brzezinski noted, but for months, even as the crisis in Iran grew, the department's own analysts said the shah could make it through the unrest.

Secretary of Defense Harold Brown, concerned about Saudi Arabia's uneasiness, had become a partial ally ofBrzezinski's. Brown said he favored letting the shah solve his own problems -- but if it took military action against demonstrators to solve them, then so be it. Brown advised the president to make it clear to the shah that the United States would stand behind him no matter what he did.

According to one National Security Council staff member, Brzezinski felt that Brown's opinion would weigh heavily with the president. Carter, the source said, considered Brown and Vance to be equally cautious in outlook. With Vance hardly involved in Iranian problems at all, Brown's views, the source said, were even more important than they would ordinarily have been.

By early November, Brzezinski told Carter that the question in Iran was no longer how the shah could move to compromise with his opponents but rather how he could restore his collapsing authority. The only way to keep the United States out of Iran in the long run, Brzezinski reportedly said, was for the shah to act decisively by turning his troops to quash dissent.

Shortly after the Walters broadcast, Brzezinski reported that Zahedi had called, upset over the television report, according to a White House source. The president had been publicly challenged to say whether he stood by the shah. The Advice

Carter told Brzezinski to call the shah and relay his support.

Brzezinski interpreted his instructions broadly. Since the beginning of the administration, his staff had repeatedly dissuaded him from recommendations for military involvement or covert action in Africa and Latin America. At this moment, Iran was the place to take a stand.

Brzezinski called that evening. According to a U.S. official who said he was familiar with the conversation, Brzezinski told the shah that Carter supported "whatever steps the shah deemed necessary to keep the peace." Brzezinski urged the shah to "crack down" on demonstrators, according to several sources familiar with the conversation. He told the shah that Carter understood that force would have to be used, and that human rights considerations were no longer of the highest priority. Brzezinski, according to one State Department source, pressed the shah to turn his government over to the military to conduct the crackdown.

Then Brzezinski called Sullivan in Tehran and informed him of his conversation with the shah.

Sullivan, feeling undercut and embarrassed, sent an angry cable to Washington, where aides to Vance were as dismayed as the ambassador was. They could not understand why Brzezinski would approve a policy of accommodation as recommended by Sullivan and then personally countermand it in a conversation with the shah. Several phone calls to Sick, Brzezinski's aide, however, confirmed that the call had been made and that Brzezinski had urged a crackdown.

Vance was also unhappy when he learned of Brzezinski's call. From almost the outset of the Carter administration, the secretary of state, according to aides, had largely ignored news reports of a constant battle for control of foreign policy between himself and Brzezinski. From his point of view, those aides said, no such battle existed. He had reprimanded his staff when they complained of power grabs by Brzezinski. This time, the aides said, Vance was truly upset. Word spread quickly through the State Department that Iran policy was now being run from the White House.

On Saturday, Nov. 4, Sullivan and British Ambassador Parsons went again to see the shah.

And the shah seemed puzzled.What was the U.S. policy? What did Carter want him to do, the shah asked Sullivan. Was it Brzezinski's advice to go ahead and unleash the Iranian military against the demonstrators? Or did the president wish something more moderate? As the shah described Brzezinski's call, he said he was not inclined to follow the advice from the White House adviser. The shah doubted that force would be effective, and again noted his conviction that his son could not rule in the future if thousands of Iranians were to be killed.

At the embassy in Tehran, however, some support for the Brzezinski position was emerging. Sullivan's deputy, Charles Naas, told a visiting team from Washington that those demonstrating against the shah were just students and religious fanatics with a large smattering of communists among them. In Naas' view, there was a "silent majority" in Iran which abhorred the demonstrations and would support a "crackdown" of the type the shah's father had employed -- when he had 25 mullahs hanged. "Human rights are no longer a problem," Naas said.

Gen. Philip Gast, the head of the U.S. military assistance group in Tehran, had a similar appraisal. All that was necessary was to concentrate on the infrastruture and management problems within the Iranian military. A member of the State Department team visiting at the time was surprised by Gast's "can do" talk. It seemed to conflict with the fact that Gast's office in the Iranian military headquarters had been without heat and electricity for a week.

On Nov. 5, the shah's attempts to bring members of the moderate opposition into his cabinet became stalled when Karim Sanjabi, a leader of the National Front, demanded along with Khomeini that the shah step down.

On that day, the worst wave of violence to date broke out. Demonstrators burned buildings and automobiles and attacked the British embassy. Tehran was aflame. Beginning to see conspiracies everywhere, some aides in the American embassy blamed the attack on the Iranian military. Sullivan thought the U.S. Embassy had been left alone because army leaders knew of the American call for repression.

That night, the shah met once more with Sullivan and Parsons. Despite his own best judgment, the shah said, he would have to let the military take command because even the moderate opposition, in the form of the National Front, had refused to deal with him.

The shah, Sullivan said, appeared composed and resolute for the first time in a long while. The shah said he had got a phone call the previous evening from Nelson Rockefeller, who told him to be tough, and that Kissinger, through Zahedi, had suggested that it was time to round up and rearrest all the political prisoners who had been released.

The shah said he would urge his military government, under the command of Gholam Reza Azhari, to rule with restraint. Some opposition leaders would be rearrested but not those of the National Front. The press would be closed for a few days because "soviets" of reporters had taken control from publishers and editors. The city would be quieted by flooding streets with troops and tanks. In contrast, some of his generals were talking about "hanging 10 mullahs or burning 10 mosques."

The shah said he was making a further attempt to split the moderate clergy, represented by the Ayatollah Shariat-Madari, away from Khomeini.

And finally, the shah told the two ambassadors, he was sure of one thing: If a military government failed to restore order, he was finished.