Adnan Badreddine (left) mourns in Beirut beneath a billboard of his brother Mustafa, one of the architects of Islamic terrorism. PHOTOGRAPH BY HASSAN AMMAR / AP

Mustafa Badreddine, a cocky Lebanese bomb maker and one of the architects of Islamic terrorism, was buried Friday. He was Hezbollah’s top military commander, and, along with his brother-in-law Imad Mughniyah, who died in 2008, masterminded one of the longest-running sprees of violence—bombings, hostage-takings, assassinations, and airplane hijackings—in the Middle East. Badreddine, who was fifty-five, was killed in a mysterious explosion in Syria, where he commanded at least six thousand Hezbollah fighters who are propping up the regime of President Bashar Assad. A few months ago, he vowed, “I won’t come back from Syria unless as a martyr or a carrier of the banner of victory.” He came back in a box.

“Along with Imad Mughniyah and a couple of others, Badreddine initiated the era of modern terror in which we still live,” Ryan Crocker, a former ambassador to Lebanon, told me today. “I could not be happier that someone killed the son of a bitch.”

Badreddine gained fame for developing a sophisticated technique for using gas to increase the power of plastic explosives. It was used in the 1983 suicide bombing of the U.S. Marine compound in Beirut, the largest loss of American military personnel in a single incident since Iwo Jima, in 1945. His name did not surface publicly until two months later, when a truck laden with forty-five large cylinders of gas connected to explosives careened through the gates of the U.S. Embassy in Kuwait. The Embassy annex crumbled; shock waves blew out windows and doors for blocks, including those of the Hilton Hotel across the street. The driver, however, rammed into the wrong building, missing the main chancery, and only a quarter of the cannisters ignited. “If everything had gone off, this place would have been a parking lot,” an American diplomat told me at the time.

Over the next few hours, five other bombs went off in Kuwait City, including one at the French Embassy. The impact unbolted a large crystal chandelier above the ambassador’s desk that missed his head by inches. Suicide bombers also struck the control tower of Kuwait International Airport, the living quarters for American employees at Raytheon, Kuwait’s largest oil refinery, and its main power station. Badreddine is credited with the idea of attacking multiple sites at the same time—a tactic later adopted by Al Qaeda, the Islamic State, and others.

“It was an extraordinary innovation,” Bruce Hoffman, the director of the Center for Security Studies at Georgetown University and a longtime terrorism expert, told me. “You can’t underestimate his influence on the patterns and tactics of terrorism today.”

Badreddine didn’t get away with the Kuwait bombings. He and twenty others were caught, and seventeen were convicted. A Kuwait court sentenced him to death, but the sentence wasn’t carried out, and he proved as dangerous in prison as at large.

Badreddine, a Lebanese Shiite, worked closely with Mughniyah, who was his cousin as well as his brother-in-law. (Mughniyah married Saada, Badreddine’s sister.) They first trained together under Fatah, Yasir Arafat’s wing of the Palestine Liberation Organization. They were then among the early recruits for a new Shiite movement fostered by Iran’s Revolutionary Guards after Israel’s 1982 invasion of Lebanon.

After Badreddine was sentenced, Mughniyah launched a spate of attacks to pressure Kuwait to free him. They included at least three commercial hijackings. The seizure of Kuwait Airways Flight 221 dragged on for six days in 1984. Two of the passengers—officials with the U.S. Agency for International Development—were shot, their bodies dumped on the tarmac in Tehran. In 1985, the hijacking of T.W.A. Flight 847 went on for two weeks. Robert Dean Stethem, a U.S. Navy Seabee diver, was shot, his body dumped on the tarmac in Beirut. And the ordeal of Kuwait Airways Flight 422, in 1988, lasted for sixteen days. Two Kuwaitis were shot, their bodies left on the tarmac in Larnaca, Cyprus. In each episode, the main demand was the release of the Kuwait 17, as Badreddine and his fellow-prisoners came to be known.

As that tactic failed to win Badreddine’s freedom, Mughniyah’s cell began to grab Americans off the streets of Beirut, launching a wave of hostage dramas that continued for seven years. Terry Anderson, the A.P. bureau chief in Lebanon, was held the longest. “My captors told me that they wanted their brothers freed from Kuwait,” Anderson told me. “They said Kuwait was an American puppet, and ‘We’ll capture Americans and they’ll tell the Kuwaitis to free our brothers.

“I’d tell them that wasn’t going to happen—and Kuwait wouldn’t listen even if they did,” Anderson said. “They would laugh and say, ‘We’ll know what we’re doing.’ ” Anderson was shocked when he heard—long after the fact—that the Reagan Administration had begun to negotiate a deal to supply arms to Iran in exchange for the freedom of the Americans in Lebanon.

“Badreddine was no common military leader,” Bilal Saab, an expert on Hezbollah at the Atlantic Council, told me. “This is a man who was so important to the organization that Mughniyah felt the need to hijack civilian airliners to liberate him, to take American hostages to free him.” The lore—among the Lebanese, former American hostages, intermediaries, diplomats, and intelligence agencies—is that Mughniyah’s wife also badgered her husband to do something for her brother.

In the end, Badreddine was freed when Saddam Hussein’s troops invaded Kuwait, in 1990. Whether by intent or accident, prisons were emptied. Badreddine soon returned to Beirut. With the fate of the Kuwait 17 no longer an issue, a path opened for the release of the Americans still held by Hezbollah. Badreddine became central to the final rounds of negotiations, led by U.N. Special Envoy Giandomenico Picco.

On four occasions, Picco was picked up by masked men in Beirut, blindfolded, and put in the trunk of a Mercedes for the ride to an undisclosed place for negotiations with Hezbollah leaders. They, too, were masked, but Picco has no doubt that they were Mughniyah and Badreddine, he told me on Friday. “Badreddine was sitting on the end of a sofa. Mughniyah was sitting adjacent in an arm chair, and I was sitting in a small chair.” Eight men with automatic rifles were also in the room. Each session ran between two and three hours. The hostage drama, which involved dozens of Americans, finally ended when Anderson was freed, on December 4, 1991. He had spent more than six years in captivity, often chained to a radiator.

Over the next decade and a half, Mughniyah and Badreddine developed the armed wing of Hezbollah into the most sophisticated militia in the Middle East, capable of fighting Israel more effectively than any other Arab army or militia, including the Palestine Liberation Organization.

Badreddine was also linked to acts of terror inside Lebanon. In 2005, an explosion rocked the motorcade of former Prime Minister Rafiq Hariri as it drove from parliament to his office. Hariri was killed. In 2011, the Special Tribunal for Lebanon, whose judges are appointed by the United Nations, indicted four Hezbollah officials and named Badreddine as chief coördinator of the Hariri assassination.

Making the connection had been difficult because Badreddine had kept such a low profile—at least under his birth name. The prosecutor, Graeme Cameron, told the court. “He has never been issued a passport. He has never been issued a driver’s license. He is not the registered owner of any property in Lebanon. The authorities have no records of him entering or leaving Lebanon. No records are held by the Ministry of Finance which would reflect that he pays any taxes. There are no bank accounts in any of the banks or any of the financial institutions in the country in his name.” He added, “Badreddine passes as an unrecognizable and virtually untraceable ghost throughout Lebanon, leaving no footprint.” He was still being tried in absentia at the time of his death this week.