SEOUL, JULY 4 -- President Chun Doo Hwan has spent most of his adult life in the South Korean Army. Thus, when he went on television the morning of April 13, he expected the 40 million citizens of his country to fall in line with the unpleasant orders he was about to deliver.

A national debate over constitutional reform was proving too divisive, Chun said in his characteristic dour tones. He had reluctantly decided to suspend it, he said, to avoid the wasting of "national energy" and to move ahead with other important tasks.

But millions of South Koreans, chafing under years of military-installed rule such as Chun's, disagreed. They had placed deeply felt hopes for change and democracy on the talks. Ending them, people said, would mean Chun's handing power to a successor of his own choice next February and years more of the same.

Chun's April 13 decision was a grand miscalculation. From it arose three weeks of startling, Korean-style "people's power" on the streets of Seoul and dozens of other cities, creating for Chun the greatest crisis ever to face his seven-year-old government.

It did not drive Chun out of the Blue House, as the heavily guarded presidential compound is known. But it forced him to decide to accept some of the most far-reaching political concessions to be found in South Korea's four-decade history. It revived hopes among many South Koreans that they can have a say in government and that liberal democracy may finally take root here.

"The decision is our people's victory," said senior dissident leader Kim Dae Jung. "It is not the outcome of Chun's good will or democratic belief."

Today, the euphoria is dying down. The tough tasks of negotiating a new form of government, fair elections and freedom for political prisoners lie ahead. New disputes are arising. Still, most people seem to feel that a page has been turned.

The potential for political upheaval was always there. The stern and distant Chun is intensely disliked. A former Army general, he is widely regarded as a military dictator. By far the biggest blot on his reputation is the killing of more than 200 people in Kwangju city in May 1980, after troops were sent in to quell demonstrations. By contrast, only two deaths were reported during the recent demonstrations -- two protesters and one policeman.

While South Korea sprints confidently into industrial affluence, people here feel that politically, theirs remains one of the world's most impoverished countries. They look at the tolerance and freedoms that go with economic development in the United States, Western Europe and Japan and cannot understand. The threat from communist North Korea seems no excuse to them.

Until June it was conventional wisdom in diplomatic circles here that the middle class would suffer in silence. Many viewed the opposition leaders as political hacks, not much better than Chun. And no one would be willing to face the riot police with whom Chun brutally broke up even the smallest of street gatherings.

People had thus pinned their hopes on constitutional reform talks that began last year and quickly became deadlocked. The opposition demanded direct election of a president, while the government insisted on a parliamentary cabinet form of government headed by a prime minister.

Seeking to break the deadlock, the opposition called mass street rallies. They brought only a small turnout of professional activists who were routed quickly with tear gas and mass arrests. In addition, cracks were appearing in the opposition party's unity, with some members saying the government's ideas should be given a hearing.

In April, the party split up in a noisy feud. The two Kims of the opposition movement, Kim Young Sam and Kim Dae Jung, left to set up a new party, taking most of the members with them.

Chun felt emboldened to move. He put Kim Dae Jung under indefinite house arrest and went on television with the "grave decision" that he had warned would come if agreement was not reached on the new constitution, apparently meaning if the opposition did not accede to the government's demands.

The next election, Chun said, would be conducted under the present constitution's system of indirect voting, which the opposition regards as rigged. Legal action was taken or threatened against various opposition members.

On the morning of June 10, delegates from the ruling Democratic Justice Party gathered at a Seoul gymnastics stadium to rubber-stamp the nomination of Roh Tae Woo, Chun's personal choice, his classmate at the Korean Military Academy and key backer in the 1979 coup d'etat that sealed Chun's rise to power. His election seemed assured.

A newly formed coalition of dissidents had called demonstrations earlier in Seoul and other cities for that evening. Everyone expected the riot police to bowl them over in a few hours.

Instead, the protests swirled out of control through the streets of central Seoul.

Columns of students, chanting "Down with military dictatorship," blocked traffic and defied tear gas and police charges. On a major avenue, they built barricades and fires and sent riot police scurrying in retreat under hails of rocks.

As things began dying down late at night, several hundred protesters made what turned out to be a brilliant move. They retreated into the grounds of Myongdong Cathedral, headquarters for South Korea's 2 million Catholics and by tradition a sanctuary.

Police settled in for a siege and Myongdong became a symbolic focus of the antigovernment fight, drawing crowds in support five days running. Every afternoon, people gathered at streets and intersections around the cathedral.

By now, street mayhem was under way in provincial cities all over South Korea. In Pusan, demonstrators staged a sit-in at the Catholic Center. In Taejon city, they thronged the main avenue night after night. Around the country, they attacked and sometimes burned police stations, riot-control vehicles and government party offices.

Unlike the 1986 revolution in the Philippines, there were no mass rallies of hundreds of thousands of ordinary citizens in one spot. The police never allowed it, attacking immediately.

But people began showing their support in other ways. Somehow the rock-throwing radicals had linked up with the population at large, something that officials had thought would never happen.

The students in Myongdong were flooded with donated food, clothing and cash and quickly became something close to national heroes, people with guts enough to say publicly what everyone was thinking.

At one point, several thousand office workers staged a festive impromptu rally outside the brick cathedral.

"There are no students here," a trading company employe pointed out proudly. "Everyone has a necktie." Soon squads of plainclothesmen were charging into them, throwing tear-gas grenades, and more people learned what it felt like to be a renegade.

Support seemed nearly universal. The mood was such that a waiter would apologize to customers that a battle outside was disrupting their dinner but note that it was "necessary for democracy." A businessman, watching thousands of students skirmish with police at the city's East Gate, would remark that "the Korean people all feel this way. It is only a few people in the Blue House who do not."

The tear gas, in particular, blanketing huge sections of the densely populated cities and choking millions of adults and children, was a radicalizing factor. The government, desperate to avoid repeating the killings at Kwangju, gave its riot police no guns. But the tear gas they relied on hit everyone for blocks around.

Important, too, was support from the church, as symbolized by Myongdong.

"We support their spirit of protest, of democracy," said the Rev. Augustine Ko at the height of the police siege. Priests pressured the government to stay off the cathedral grounds, keeping the siege alive as a rallying point.

Not much is known of what was happening at this time inside the Blue House. It is clear, though, that within days, officials there were holding emergency meetings, thinking of storming Myongdong. By some authoritative accounts, they came close to imposing some form of martial law. In the end, though, they chose to talk peace.

South Korea is scheduled to be the site of the 1988 Summer Olympics and has a world reputation to uphold. Nothing stung officials here more than public offers at the height of the crisis by Los Angeles and other cities to take the games if Seoul proved incapable of holding them.

South Korea is also fast becoming a significant industrial power, with $35 billion last year in exports, a foreign aid program, even expeditions to Antarctica. Martial law had no place in the image South Korea wants to cultivate abroad.

And there was Chun himself. He has long given signs that he is something more than a simple military ruler. Diplomats said he deeply values his place in history and is desperate not to follow his predecessor Park Chung Hee in using martial law whenever faced with a difficult challenge.

But many people here also believe Chun may have seen martial law as potentially suicidal. There is little doubt that the country's highly disciplined officers and troops would have gone into the streets if ordered, but if things reached the point at which they had to shoot demonstrators, their attitude might have changed.

The troops did that in Kwangju in 1980 and suffered forever in the public eye for it. No one in uniform wants a repetition. Similar killings, many people believe, might have encouraged officers to invite Chun to solve the problem by removing himself.

Another factor was constant cajoling from the United States, South Korea's patron and protector. Its efforts surprised many people in the opposition, who have long seen Washington as generally supporting Chun.

Three days after the crisis began, Ambassador James Lilley firmly advised Korean officials not to assault the cathedral. The following week, Assistant Secretary of State for East Asian Affairs Gaston Sigur flew in to call on government and opposition leaders with what he called a "crystal clear" message that the problems should be solved by peace and compromise, not martial law. A steady stream of similar, public statements came out of the State Department and Congress.

By most accounts here, Washington played a significant but not pivotal role in Chun's ultimate decision. The dynamics of South Korean society were already moving things in the direction of a dramatic back-down.

Within days, the government was giving signals that it wanted to talk. On June 24, Chun conferred with Kim Young Sam; it was the first time they had ever met. He offered to release Kim Dae Jung from house arrest and resume discussions on amending the constitution. Kim Young Sam scoffed, saying the demonstrations would continue if that was the best the government could do.

Continue they did. On June 26, tens of thousands of people gathered in Seoul and more than 30 other cities for a "Grand Peace March." Once again the streets were transformed into battle zones of firebombs, rocks and tear gas.

Three days later, ruling party leader Roh stunned the government and opposition camps alike with a television announcement that he favored granting virtually all of the opposition's demands -- direct elections, full political rights for Kim Dae Jung, release of political prisoners. He said he would resign if Chun did not agree.

"All of us are responsible for avoiding the national disgrace of dividing ourselves and thus causing the world to ridicule us," Roh said.

Newspapers rushed out extra editions hailing his move. Word sped through coffee shops and offices. Within hours, praise was pouring in from abroad. Two days later, Chun went on television to announce that he agreed to all of it.

With one stroke, the government had cut the much-feared link between ordinary citizens and radicals. Not only that, it had given Roh legitimacy with the public for the first time, as the man who had faced up to Chun. Many people, however, think Chun was in on the deal all along.

Roh has since moved into a high-gear presidential campaign. He has prayed at a patriotic shrine, visited the parents of a student left in a coma by a flying tear gas canister, called on Kim Young Sam unannounced and received a hostile group of families of political prisoners. The injured student died today.

Will the public prefer for president a reasonable former general over a professional opposition gadfly? The ruling party is gambling that the answer is yes. Many other analysts say no, that Roh remains too tarnished by his association with Chun to win a fair direct election.

But that is assuming that the opposition fields just one candidate. Newspapers here have wasted no time in finding cracks in the alliance between the two Kims. There are also minor opposition figures who might enter the race and take some votes from them. The government may be counting on such a split vote in the election, which is supposed to take place late this year.

Government people, meanwhile, are rubbing their hands with glee over the dramatic settlement. Somehow, they have been made to look for the first time in years like thoughtful, compassionate people who hold the national interest above their own.

In the opposition, however, not everyone is sure they have victory. Yesterday, thousands of students massed peacefully at Yonsei University to declare that their fight will go on, since they see the government as incapable of acting in good faith. And many moderates, too, are waiting to see if it really delivers on its promises.

Unanswered also is the question of whether institutions of control that Chun has created are going to melt away. The country has more than 60,000 riot police. It has a huge domestic security apparatus that replaced the former Korean Central Intelligence Agency, as well as the police and the military security command. People there have made careers of clamping down on dissent and will not want to stop.

Perhaps most important, however, is the absence of a democratic tradition in South Korea. People here almost worship democracy but have no idea of how it works. Traditional beliefs stress loyalty and strong, wise leaders.

That is why Chun could handpick a successor and call it democracy. And that is also why Kim Dae Jung can tell visitors that he and Kim Young Sam will settle the question of who will run for president from the opposition side, making no mention of consulting the public or party members.