South Korea’s military — agents of terror and violence in the 1970s and ’80s — spent decades scrupulously cleaning up its image to become what many people in the country came to see as a modern and disciplined force.

But that image was shattered on Thursday when the general who led a short-lived spasm of martial law this week was grilled in Parliament, a rambling appearance that cast the military as ill-prepared and disorganized from the top down.

“We were not militarily prepared because it was put into action in such a hurry,” Gen. Park An-su, the Army chief of staff, told a parliamentary hearing on Thursday. “There was confusion.”

His testimony offered the first opportunity for lawmakers to question the military about the martial law order handed down on Tuesday night by President Yoon Suk Yeol. The decree plunged the country into a political crisis, sparking widespread anger that drove thousands of protesters to the streets. Mr. Yoon was forced to reverse course after just six hours.

General Park insisted that he had not had any role in the planning: He told lawmakers he had been caught off guard, first learning of it when Mr. Yoon announced the extraordinary move on television. The military’s follow-up announcement, under his name, banned “all political activities” and public rallies and asserted control over media outlets, among other steps. But in his account on Thursday, General Park claimed he had not read it until his signature was requested.

He described being at a loss over how to proceed as commander, unsure of what steps to take beyond trying to set up a new office.

“We were military people, some of us the best I know,” General Park said of a meeting with aides after he was made martial law commander. “But we didn’t know much about martial law. Time passed while we wondered, ‘What should we do?’”

His testimony was clearly aimed at rebutting the idea that the military had returned to its old, brutal ways. But it appeared unlikely to ease any of the anger from protesters — some of whom had lived through the traumatic era of military rule and had been part of the popular uprising that ushered in South Korea’s democracy.

In the 1970s and ’80s, the military used martial law to send troops into towns and college campuses to violently suppress anti-government protesters, massacring hundreds. It censored the news media, hauling unfriendly journalists into torture dungeons. Army generals beat up lawmakers.

South Koreans fought back with stones, firebombs and massive protest rallies. By the 1990s, the generals who had taken power through coups and bloodshed were in prison on charges of mutiny. The military worked to clean up its image, vowing not to meddle in politics.

Many South Koreans believed them. That’s why footage broadcast on Tuesday night of helicopters dropping elite troops to take over the National Assembly deeply shocked the nation. Emblematic of the rage was the scene of a young woman grabbing a paratrooper’s rifle barrel on Tuesday night at the Assembly, yelling: “Shame on you!”

The woman, An Gwi-ryeong, had rushed to the Assembly after the martial law declaration to find troops trying to force their way into the building to prevent lawmakers inside from voting to repeal the order. Citizens and parliamentary staff were resisting the troops.

“I thought we had to stop them no matter what,” Ms. An, a spokesman of the main opposition Democratic Party, said in an interview. “I thought if they broke in, we had no future.”

Ms. An, 35, grew up in a democratized South Korea: Her knowledge of martial law came from history textbooks and movies. When some lawmakers in her party suggested that the deeply unpopular Mr. Yoon could deploy martial law to silence his critics, she said she wondered whether he might do it.

“When it actually happened, it felt not real, this happening in the 21st-century South Korea,” she said. “There is a lot of blame for the military, but the one who is to blame the most is Yoon Suk Yeol, who made his military train its guns at its own citizens.”

The hearings on Thursday were an attempt to understand how and why that happened. The questioning lasted hours and appeared tense at times, as lawmakers raised their voices in frustration.

General Park told them he still did not know who had ordered the troops to storm the National Assembly — a striking claim from the man who was ostensibly their commander. When some lawmakers urged him to resign, General Park said he had already offered to do so.

The country’s deputy defense minister, Kim Seon-ho, testified that the defense minister, Kim Yong-hyun, had ordered in the troops — a move he said he had opposed.

“I am sorry to the people for having been unable to prevent or stop it,” he said.

The defense minister, a former bodyguard of the president, resigned before the hearings and did not testify.

In an interview with The New York Times, one opposition lawmaker, Park Sun-won, who had formerly served as a deputy chief of the National Intelligence Service, said that his bloc had received an advance tip about the military’s movements. The notice gave lawmakers a head start to get to the National Assembly and conduct their vote to reject martial law before the military could break in to stop them.

The military’s failed attempt to take over the Assembly has formed a central piece in the opposition’s argument for why Mr. Yoon should be impeached for “insurgency.”

Mr. Yoon has not been seen in public or made a public statement since the early hours of Wednesday. He had insisted that martial law was necessary to protect the country from an extremely disruptive “anti-state” opposition that he said paralyzed his government.

The National Assembly is scheduled to vote on Saturday about whether to move forward with impeachment. Opposition lawmakers have a majority in the legislature, but an impeachment motion needs a two-thirds vote to pass. That would require some support from members of Mr. Yoon’s party.

The opposition is hoping to take advantage of mass demonstrations scheduled for Saturday to create extra pressure as the vote takes place.

Mr. Yoon has been struggling with abysmal approval ratings for months. One of the first nationwide opinion polls conducted after the martial law suggested overwhelming public disapproval of his latest move. More than 70 percent of South Koreans are in favor of impeaching him, according to the poll conducted by Realmeter, based in Seoul.

The president, who was exempted from South Korea’s mandatory military service because of eye trouble, has had support from many military veterans, thanks to his conservative hard line on North Korea and his efforts to expand military ties with the United States.

But on Thursday, old Marine veterans rallied against him near the presidential offices, calling Mr. Yoon the “mastermind of insurgency.”

“Let’s decapitate Yoon Suk Yeol!” they chanted, holding a large banner with the same slogan.

The number of protesters on the streets of Seoul swelled as evening fell, with hundreds of people converging near City Hall. Unlike the many routine protests in the city’s center that are dominated by retirees, the rally featured a vibrant cross-section of the city, grandparents standing shoulder to shoulder with students and parents with children.

People gave speeches and led chants, with “Yoon Suk Yeol must resign” as a common refrain.

Kim Sung-hwan, 67, was in the crowd. During military rule in the 1980s, he helped enforce martial law against protesters, sometimes violently.

“I came because things should never be like that again,” he said.

Victoria Kim and John Yoon contributed reporting.

Syrian rebels stormed into the city of Hama on Thursday as government forces withdrew, another stunning setback for President Bashar al-Assad.

The swift advance on Hama, which was confirmed by both the rebel side and the Syrian government, comes just days after the rebels extended their control over Aleppo, a major hub in northern Syria.

The sudden rebel advance has shifted the front lines in Syria’s 13-year-old civil war for the first time in years, adding a new layer of unpredictability to a conflict that has ravaged the country and created a long-term refugee crisis for many neighboring countries.

Analysts have attributed the rebel’s surprise success to the cumulative attrition of the war on Mr. al-Assad’s forces and to the fact that foreign allies who have intervened powerfully on his behalf in the past — notably Russia, Iran and the Lebanese militant group Hezbollah — are now preoccupied with their own crises.

Hezbollah, which is backed by Iran, is recovering from a war with Israel that killed many of its leaders and displaced many of its supporters. And Russia — which dispatched its military to bomb rebel areas, turning the war’s tide in favor of Mr. al-Assad years ago — has diverted its attention toward its invasion of Ukraine.

The rebels behind the offensive are a combination of forces led by Hayat Tahrir al-Sham, which evolved from an affiliate of Al Qaeda. But the group says it has cut ties with the global terrorist organization. Other groups backed by Turkey and based in Syrian territory just south of the Turkish border have also joined in the fight.

The rebels announced on Thursday that they were entering Hama, one of Syria’s largest cities. A rebel commander, Lt. Col. Hassan Abdulghany, said in a social media statement that government forces were in “a significant state of confusion,” with soldiers and commanders abandoning their posts.

The Syrian military issued its own statement, saying that its forces had withdrawn from the city after rebels broke through its defenses.

Amnesty International on Thursday became the first major international human rights organization to accuse Israel of carrying out genocide in Gaza, drawing a rebuke from Israeli officials who denied the claim.

Amnesty’s contention, outlined in a 296-page report, comes as the International Court of Justice, the principal court of the United Nations, is reviewing similar allegations by South Africa.

“Israel committed and is committing genocide against Palestinians in Gaza,” the Amnesty report said.

The Israeli Foreign Ministry swiftly rebuffed the report, saying it was “based on lies.”

“Israeli citizens have been subjected to daily attacks” on multiple fronts, said Oren Marmorstein, the spokesman of the ministry. “Israel is defending itself against these attacks acting fully in accordance with international law.”

Amnesty International said it took into account acts by Israel between October 2023 and July 2024, including what it described as “repeated direct attacks on civilians” and extensive restrictions on humanitarian aid.

Israel has maintained that it is waging a war against Hamas in Gaza and not civilians. It has also blamed the United Nations for mismanaging the delivery of aid and accused Hamas of looting it.

The genocide accusation is acutely sensitive for Israel, which was founded in 1948 in the aftermath of the Holocaust. Many Israelis argue that it is Hamas that should face charges of genocide after its attack on Oct. 7, 2023, when about 1,200 people were killed in Israel and about 240 were taken captive, according to Israeli officials.

While the Amnesty report didn’t focus on the Oct. 7 attack, it said militants from Hamas and other armed groups conducted “deliberate mass killings, summary killings and other abuses, causing suffering and physical injuries.” It said war crimes committed by Hamas would be the subject of a separate report.

Under a convention adopted by the United Nations General Assembly in 1948, genocide is defined as carrying out certain acts of violence with the “intent to destroy, in whole or in part, a national, ethnical, racial or religious group.”

In the case before the International Court of Justice, South Africa has argued that inflammatory public statements made by Israeli leaders are proof of intent to commit genocide. Part of Israel’s defense is to show that whatever politicians may have said in public was overruled by executive decisions and official orders from Israel’s war cabinet and its military’s high command.

Amnesty International said it used the 1948 convention to make its determination that Israel was committing genocide and it warned against narrow interpretations of what constitutes intent.