Thomas Polgar, the last CIA station chief in Saigon during the Vietnam War, who helped direct the frantic airborne evacuation of U.S. citizens and Vietnamese leaders during the final days of the war in 1975, died March 22 at his home in Winter Park, Fla. He was 91.

His wife, Anna Polgar, confirmed the death but said she did not know the exact cause.

Polgar, a native Hungarian who served in a U.S. espionage agency in World War II, joined the CIA at its founding in 1947. He spent years working in Europe and Latin America before going to Saigon in 1972 to take over what was the largest CIA station in the world.

“He was a legend in the institution,” Jack Devine a former CIA station chief, said in an interview. “If you would look at him, he’s the last guy you would think was in the spy business.”

Balding and bespectacled, with a noticeable Hungarian accent, Polgar exhibited few trappings of power and often commuted to work on his bicycle. Nonetheless, he had ready access to the highest levels of the CIA, White House and Pentagon and often attended meetings with President Richard M. Nixon and Henry A. Kissinger, the national security adviser and later secretary of state.

When Polgar took over the Saigon station, the CIA director was Richard Helms, an old friend from the Office of Strategic Services during World War II. “If somebody were to assign Tom Polgar to go after me,” Helms said in 1988, “I would really be worried about it. He gets his man.”

In Vietnam, Polgar had command over a network of 550 CIA officers, including 200 who worked undercover, according to journalist Tim Weiner’s 2008 CIA history, “Legacy of Ashes.”

By the time Polgar arrived in Saigon, congressional and public support for the war in the United States was in free fall. U.S. ground forces were withdrawn soon after the Paris Peace Accords of 1973, which led to a tentative agreement to end the war. The Nixon administration was consumed by the Watergate scandal, which led to the president’s resignation in August 1974.

Amid the chaos, Polgar was instructed by the White House to “preserve a non-communist Vietnam.” But as that goal became increasingly unlikely, he sent a message to Washington, citing a lack of leadership: “We are a rudderless ship.”

In April 1975, historians have noted, Polgar recommended that South Vietnam’s president, Nguyen Van Thieu, be ousted in a coup. A new leader could then form a coalition government with the communist insurgency. The idea was rejected by Polgar’s bosses.

Thieu resigned under pressure on April 21, and Polgar was in charge of spiriting him and other Vietnamese officials out of the country. Thieu was driven to the airport at night in a car with the headlights turned off.

By April 29, Saigon was under siege. The airport was bombarded, and the U.S. armed forces radio station ran an announcement that was in fact a coded message to begin the evacuation of Saigon: “The temperature in Saigon is 105 degrees and rising,” followed by 30 seconds of Bing Crosby singing “White Christmas.” It was repeated every 15 minutes.

Polgar helped select Vietnamese employees and their families to be flown to safety by helicopter. Many were left behind.

On April 30, North Vietnamese soldiers entered Saigon, and the sounds of artillery and gunfire could be heard throughout the city. At one point, Polgar recalled in a blog post he wrote in 2013, he took cover under his desk.

The U.S. Embassy was officially closed, and Americans were ordered to leave Saigon by nightfall. Polgar found himself surrounded by the din of people clamoring to leave, the chopping rotors of helicopters and the general bedlam of a decade-long war coming to an end in a single day.

The U.S. ambassador, Graham Martin, took the American flag with him as he and his staff departed the embassy.

Polgar stayed behind. His final job was to burn the CIA’s files. Cables, code books, pictures and anything hinting at an employee’s identity went into an incinerator.

After midnight, he sent his last cable from Saigon, a sharply worded message that has entered CIA lore.

“This will be final message from Saigon station,” he wrote in a clipped, telegraphic style. “It has been a long fight and we have lost. . . . Those who fail to learn from history are forced to repeat it. Let us hope that we will not have another Vietnam experience and that we have learned our lesson. Saigon signing off.”

Polgar then destroyed the machine on which he sent the cable.

At 4:40 a.m. on May 1, 1975, he climbed aboard a helicopter that took him away from Saigon.

Thomas Polgar was born July 24, 1922, in Budapest, where his father was a banker. Polgar was 16 when he left Hungary to study accounting at a business school in New York City.

After World War II broke out, he could not return to his homeland because Hungary was part of the Axis alliance fighting against the United States. At the suggestion of an FBI agent he met in New York, Polgar wrote a letter to then-first lady Eleanor Roosevelt, explaining his predicament.

Within weeks, a New York congressman helped arrange for Polgar to join the U.S. Army and become an American citizen. He was fluent in several languages and was soon recruited to the OSS spy service.

After serving as an aide to Lucian K. Truscott Jr., an Army general who became a top CIA official, Polgar spent much of the 1950s and early 1960s in Berlin, where he cultivated a far-flung ring of spies. One of his agents was a teletypist whose sister was having an affair with a police officer with connections to the Soviets. The lovers had their trysts in Polgar’s apartment in Berlin.

Polgar was working in the Latin American division at CIA headquarters when Argentine-born revolutionary Ernesto “Che” Guevara — who helped foment the Cuban Revolution with Fidel Castro — was captured and killed in Bolivia in 1967.

Polgar wanted the CIA’s station chief in La Paz to verify that Guevara was dead.

“Can you send fingerprints?” he asked.

The reply: “I can send fingers.”

Polgar was station chief in Buenos Aires in the early 1970s, and after Saigon he ran the CIA’s stations in Mexico City and Bonn, Germany. He retired in 1981. He received the Distinguished Intelligence Medal twice, the State Department Award for Valor and the CIA’s Intelligence Star for “outstanding achievements or services rendered with distinction under conditions of grave risk.”

His first marriage, to the former Patricia Williams, ended in divorce. Survivors include his wife of 36 years, Anna Fain Polgar of Winter Park; three children from his first marriage, Thomas C. Polgar of Springfield, Va., Patricia Polgar-Bailey of Charlottesville, Va., and Catherine P. Jordan of Waterford, Conn.; and four grandchildren.

In later years, Polgar was an analyst for the Senate select committee investigating the Iran-Contra scandal of the 1980s, and he worked as a consultant on defense and counter-terrorism. He was often consulted by historians and journalists writing about the CIA and the last days of Saigon.

Inside the halls of the CIA, Polgar was known for his blunt assessments of conditions in the field. He held no illusions about the nature of his profession, but he understood that the spy trade sometimes had to be carried out regardless of its danger and moral ambiguity.

“When you engage in espionage, you engage in activity that is completely illegal,” he told the New York Times in 1995. “You are engaged in a conspiracy to commit a crime.”