Story highlights "Farewell to the grandest, most buoyant, most generous soul I ever knew" -- Hillenbrand

Louis Zamperini is the subject of bestseller and upcoming film "Unbroken"

Zamperini survived plane crash, weeks on raft, Japanese POW camps

After World War II, he became inspirational speaker

Louis Zamperini, the Olympic runner and World War II officer who survived a horrific plane crash, a seven-week journey across the Pacific in a raft, near starvation and unspeakable torture in Japanese POW camps, has died.

He was 97. The cause of death was pneumonia, his family said in a statement from Universal Pictures, which is making a film adaptation of "Unbroken," Laura Hillenbrand's bestselling chronicle about Zamperini's life

"Having overcome insurmountable odds at every turn in his life, Olympic runner and World War II hero Louis Zamperini has never broken down from a challenge. He recently faced the greatest challenge of his life with a life-threatening case of pneumonia. After a 40-day long battle for his life, he peacefully passed away in the presence of his entire family, leaving behind a legacy that has touched so many lives," the Zamperini family said in a statement.

"His indomitable courage and fighting spirit were never more apparent than in these last days."

Louis Zamperini with "Unbroken" director Angelina Jolie in October. The film, based on the bestseller about his life, comes to theaters this Christmas.

On her Facebook page, Hillenbrand wrote , "Farewell to the grandest, most buoyant, most generous soul I ever knew. Thank you, Louie, for all you gave to me, to our country, and to the world. I will never forget our last, laughing talk, your singsong 'I love you! I love you!' and the words you whispered to me when you last hugged me goodbye, words that left me in happy tears, words that I will remember forever. I will love you and miss you to the end of my days. Godspeed, sweet Louie."

Angelina Jolie, the director of the "Unbroken" film, added, "It is a loss impossible to describe. We are all so grateful for how enriched our lives are for having known him. We will miss him terribly."

Zamperini's tale is one of those that would be dismissed as fiction if it weren't true.

A wild child who grew up in Torrance, California, he was tamed by a love for running and an unquenchable competitiveness. At 19, he ran the 5,000 meters at the 1936 Olympics in Berlin despite mere weeks of training at that distance. He missed a medal but, in his determination to catch the leaders, ran his last lap in an astonishing 56 seconds.

With the 1940 Olympics canceled due to the outbreak of World War II, he enlisted in the Army Air Corps prior to Pearl Harbor and eventually became a bombardier on the sometimes unwieldy B-24 Liberator, nicknamed the "Flying Brick." In late May of 1943, he and a crew took off on a search mission for a fallen pilot. Somewhere over the open Pacific, the plane failed and crashed into the ocean.

Zamperini and two colleagues survived, but their troubles were just beginning.

He and the other crew members had to survive 47 days on a raft, in scorching sunlight and often without drinking water. They collected rain when it fell and killed albatrosses who alit on the raft. Sharks constantly circled beneath them. One person died on the journey.

When Zamperini and his buddy, pilot Russell Allen "Phil" Phillips, finally washed ashore on a Pacific island, they found they had drifted 2,000 miles -- only to be taken in as prisoners of war by the Japanese.

Life only got harder. The men were fed poorly and feared being killed by their captors. Zamperini was singled out for abuse by one camp sergeant, nicknamed "the Bird," who beat him regularly in psychotic fury.

Zamperini was declared dead by the U.S. military.

Zamperini, a University of Southern California alumnus, serves as a presenter at the Golden Goggle swimming awards in Los Angeles in 2011.

Yet he endured.

As documented in "Unbroken," after the war, Zamperini struggled to adjust. He drank heavily. He had trouble sleeping. He wanted revenge on the Bird. But, thanks to a newfound faith -- inspired by visits to Billy Graham's Los Angeles Crusade in 1949 -- and an unshakable spirit, he overcame his troubles and became an inspirational speaker.

He established a camp for troubled youths called Victory Boys Camp. His wife, Cynthia, was a cornerstone of his life. They were married for more than 50 years, until her death in 2001.

He also forgave his wartime tormenters, some of them in person during a 1950 visit to a Tokyo prison where they were serving sentences for war crimes. He was willing to forgive the Bird, Mutsuhiro Watanabe, though Watanabe refused to meet with Zamperini when he had the chance, in 1998, when Zamperini returned to Japan to carry the torch at the Nagano Winter Games.

Scott Blackmun, CEO of the U.S. Olympic Committee, issued a statement offering condolences to the family and saying, "We're proud to say that among his many accomplishments and triumphs, Mr. Zamperini was an Olympian. His fighting spirit was a true representation of Team USA and our country, both in Berlin and throughout his life. His presence will be missed."

Hillenbrand's book was released in November 2010. It remains on the bestseller lists almost four years later.

Jolie's movie is scheduled to be released Christmas Day.