Then-Capt. Louis Zamperini, former Olympic track star, who survived 47 days on a life raft in the Pacific when his bomber crashed, greets his wife to be, Cynthia Applewhite, in 1946. (AP)

Louis Zamperini, a onetime Olympic runner who survived 47 days on a raft in the Pacific and two years as a Japanese prisoner during World War II, and whose story was retold in the best-selling biography “Unbroken,” died July 2 in Los Angeles. He was 97.

The cause was pneumonia, his family said in a statement.

Mr. Zamperini wrote about his wartime ordeal in two memoirs, but it wasn’t until 2010, when Washington author Laura Hillenbrand published “Unbroken,” that Mr. Zamperini’s harrowing story captured the public’s imagination. A film about his life, directed by Angelina Jolie, is scheduled to be released Christmas Day.

“Rarely,” author Gary Krist wrote in his review of “Unbroken” in The Washington Post, “has a single man had to endure such an extraordinary array of woes.”

Even before his experiences during the war, Mr. Zamperini had led a remarkable life. In the 1930s, he was of the best distance runners in the world and was considered a threat to become the first person to break the four-minute barrier in the mile.

He competed in the 5,000-meter run in the 1936 Olympic Games in Berlin and was considered a favorite in the 1940 Olympics, which were scheduled for Tokyo but never took place because of World War II.

Instead, Mr. Zamperini enlisted in the Army Air Forces and became a bombardier on B-24 Liberators in the Pacific. On May 27, 1943, he and the rest of his crew were on a search-and-rescue mission 800 miles from Hawaii when the aircraft developed mechanical problems and dived nose first into the ocean.

He was one of three crew members to survive the crash. Trapped under water and wrapped in torn coils of electrical wire, Mr. Zamperini found his bearings when his class ring from the University of Southern California caught on a piece of metal. He was able to swim out of the wreckage as it drifted toward the ocean floor.

He and the other crew members climbed into a rubber life raft that had few provisions. As they drifted in the open sea, they improvised ways to capture rainwater. Mr. Zamperini fashioned the pin of his lieutenant’s insignia into a fishhook, with little success.

Sharks circled the small inflatable raft, which sprang leaks as the rubber weakened under the relentless sun. One day, a Japanese warplane strafed their lonely craft, forcing them to dive into the water with the sharks.

The three castaways survived by catching birds with their bare hands and using the entrails for fish bait. When a tern landed on the raft, “Louie was so famished that he went at it with his teeth, ripping the feathers loose and spitting them out in whuffs,” Hillenbrand wrote in “Unbroken.”

“Almost immediately, he felt a crawling sensation on his chin. The tern had been covered in lice, which were now hopping over his face.”

From a college physiology course, Mr. Zamperini recalled that the brain was a muscle that could atrophy from disuse. He and his fellow airmen told stories about their lives and repeatedly sang “White Christmas” to an empty ocean.

In place of regular meals, they recalled their favorite foods in elaborate detail.

“Louie began describing a dish, and all three men found it satisfying, so Louie kept going,” Hillenbrand wrote, “telling them about each dish in the greatest possible detail. Soon, [his mother’s] kitchen floated there with them: Sauces simmered, spices were pinched and scattered, butter melted on tongues.

“So began a thrice-daily ritual on the raft, with pumpkin pie and spaghetti being the favorite subjects.”

After 33 days, one of the three crew members died. Mr. Zamperini and the other survivor, Russell Allen Phillips, improvised a funeral ceremony and buried him at sea.

They stayed afloat for an additional 14 days, through rainstorms that stirred up 40-foot waves and nearly capsized their tiny raft.

Mr. Zamperini and Phillips were within sight of an island when a Japanese motorboat pulled alongside their raft. The emaciated Americans were taken captive at gunpoint, their hands bound behind their backs. Mr. Zamperini, who stood 5-foot-9 and weighed about 160 pounds when his flight took off May 27, had shrunk to about 80 pounds.

He and Phillips were shipped to separate POW camps. (Phillips survived the war and died in 1998.) Adrift for 47 days, they are believed to have survived the longest time at sea without provisions.

By strange chance, a Japanese officer at one of the camps had studied at the University of Southern California and recognized Mr. Zamperini. The Japanese thought a star athlete would have propaganda value, but Mr. Zamperini refused to denounce his country. He was then subjected to almost daily torture from a sadistic guard he called “the Bird.”

In the meantime, Mr. Zamperini was officially declared dead, and his parents received a letter of condolence from President Franklin D. Roosevelt.

After the Japanese surrendered in August 1945, Mr. Zamperini and 700 other prisoners were released. They knew they were free when a U.S. plane flew over the prison, and the pilot dropped a small package from the cockpit. It contained a pack of cigarettes and a chocolate bar.

The prisoners sliced the chocolate bar into 700 slivers, giving each man a faint taste of freedom.

Louis Silvie Zamperini was born Jan. 26, 1917, in Olean, N.Y., and moved with his family to Torrance, Calif., in 1920. His parents spoke Italian at home, and young Louie, as he was called, didn’t learn English until he went to school.

He had a troubled childhood and was smoking by age 5 and drinking at 8. He seemed headed for a life of delinquency when his older brother, a champion miler, encouraged him to start running.

Known as the “Torrance Tornado,” Mr. Zamperini won the 1934 California state championship in the mile with a time of 4 minutes, 21.8 seconds — a national high school record that stood for 19 years. In 1936, he won a spot on the U.S. Olympic team in the 5,000 meter-race. He was 19 at the time — still the youngest U.S. male runner ever to compete at that distance in the Olympics.

At the “Hitler Olympics” in Berlin, Mr. Zamperini was near the back of the pack when he decided to sprint the race’s final lap at top speed. He ran the final 400 meters of the race in a remarkable 56 seconds to finish in eighth place.

Afterward, he was invited to greet Hitler, who said, “Ah, you’re the boy with the fast finish.”

At USC, Mr. Zamperini won two national championships in the mile and in 1938 set an NCAA record at 4:08.3, the fifth-fastest mile in history at the time. His collegiate record stood until the 1950s.

After the war, Mr. Zamperini was reunited with his family in California and, in 1946, married Cynthia Applewhite. He struggled with alcohol and was haunted by painful memories until his wife took him to a revival meeting led by evangelist Billy Graham in 1949.

“It was the first night in two years and a half that I didn’t have a nightmare,” Mr. Zamperini told CBS News in 2012, “and I haven’t had one since.”

He quit drinking and smoking and became a devout follower of Graham’s. He spent many years working in real estate and coaching track in California and founded a camp for troubled youth and became an motivational speaker, often addressing military groups about his imprisonment.

His wife died in 2001. Survivors include two children and several grandchildren.

He returned to Japan many times over the years as a gesture of friendship and forgiveness. His onetime guard, “the Bird,” refused to meet with him despite Mr. Zamperini ‘s repeated entreaties.

Before the 1998 Winter Olympics in Nagano, Japan, Mr. Zamperini carried the Olympic torch, cheered at every step by a new generation of Japanese.