Fifty years ago, in that tranquil fall of 1963, Liz Pozen was a young suburban mother living in Chevy Chase, Maryland. Her husband was a lawyer at the Department of the Interior, and she was a stay-at-home mom, typical of that time. The only unusual part of her life, some would call it extraordinary, was that when she took her six year old daughter, Agatha, to school, she drove her Country Squire station wagon through the southwest gate of the White House. The guards knew the car and would wave her through. Fifty years ago, that’s how security worked at the Executive Mansion.

Jacqueline Kennedy had organized a school upstairs in the family residence for her daughter, Caroline, and 12 other children. Sometimes when Agatha forgot her lunch, Liz would drive back, take it upstairs and more than once ran into the President as he was coming down.

The First Lady tried to find ways to make her children’s lives as normal as possible. So that fall, she and Liz agreed that it would be a great idea for Caroline to have a sleepover at Agatha’s house, just like two little girls anywhere else. It was difficult to find the right time, given the hectic calendar of the nation’s First Family, but the two mothers zeroed in on what they thought was the perfect weekend – when the President and First Lady would be away in Dallas.

Just after school let out on that Friday afternoon, November 22nd, Liz was driving up Connecticut Avenue with a lone secret service agent following in an unmarked car. The two girls were giggling in the back seat, eager with anticipation of the sleepover. Then the bulletin came over the classical station Liz was listening to, forever changing their lives and the course of the world.

It was at that moment that Elizabeth Pozen, suburban mom in a Country Squire with two little girls in the back seat, became a supporting character in a four day drama that would captivate us for the next half-century.

Just as World War II had created the demarcation “before the war” and “after the war,” the assassination of President John F. Kennedy marked a similar divide for most Americans.

“Our country changed after that.” Liz Pozen recalls, looking back over half-a-century. “I suppose we changed as well.”

A scant ten weeks later, in February 1964, when the country was still struggling to come to grips with the killing in Dallas, William Manchester was sitting at his desk at Wesleyan University when the telephone rang. At the time, Manchester was teaching undergraduates while working on a history of the Krupp arms manufacturing family. He had already published seven relatively obscure books – his stature was far from what it would be in the decades to come.

The journeyman historian was caught off guard when Pierre Salinger, on the other end of the phone, told him that Jacqueline Kennedy had chosen him to write the official history of the assassination the President.

At that moment, the former First Lady was the most sought after woman in the world. Interview requests arrived daily and each one was rejected. As difficult as it may be to comprehend in today’s celebrity-driven media, she would not talk. That silence only heightened every journalist’s desire to interview her. So it was strange and fortuitous that she would reach out to a relatively unknown writer like Manchester. Only later would the author understand why he was chosen among all the other writers in the world.

“My first impression and it never changed,” Manchester later wrote about Mrs. Kennedy, “was that I was in the presence of a great tragic actress.”

Manchester did not mean that in a demeaning way. With tremendous dignity and poise that seemed beyond the grasp of someone who was only 34 years old, Jacqueline Kennedy orchestrated a national funeral with a ceremonial pomp unknown in America. She almost single-handedly brought the United States through one of its darkest weekends. There were few people anywhere who would not have done anything she requested.

Jacqueline Kennedy contacted Manchester because she was aware that other writers, some of whom she considered hacks, were already starting books on the assassination. She thought that if she chose the writer, she could control the outcome. Given her stature at that time, she may have been correct.

“I spoke to Manchester because Jackie asked me to,” Liz Pozen explains, proving the point. “Otherwise, I never would have talked about it.”

Mrs. Kennedy told Manchester she had chosen him because the late President held him in high regard. But he doubted the flattery. In 1962, Manchester had written an article for Holiday Magazine entitled “Portrait of a President.” Manchester came to suspect he was picked because he had sent the Holiday galleys to the White House for the President’s approval out of respect for the office.

“As it happened,” Manchester later wrote, “He requested no changes, but Jackie may well have concluded that the incident proved that I would be infinitely obliging.”

“It is a natural mistake.” Manchester added.

What followed for Manchester was a three-year journey into grief, a public fight with one of the most powerful families in America and, ultimately, one of the best modern history books ever written. Fifty years after the event, Manchester’s “The Death of a President,” stands out as the most authoritative, factually correct and captivating book on the Kennedy assassination.

However, the process of writing the book and even getting it published would be as painful for the author as the event itself.

Manchester agreed to all of the terms set forth by the Kennedys before he began writing. Except for a publisher’s advance of $36,000 to be paid in installments, all the author’s proceeds after the first printing would go to the Kennedy Library. The Kennedys chose the publisher, Harper & Row, as well as the editor, Evan Thomas.

There was one more provision that would prove to be the hinge on which the controversy would turn: the book could not be published unless both Mrs. Kennedy and her brother-in-law Robert approved the manuscript.

Manchester rented a small room in Washington working 15-hour days, seven days a week. To save bus fare, he walked everywhere throughout the hottest months in the District. He personally conducted all the interviews and transcribed his own notes.

The author interviewed everyone from the key figures — the Kennedy family, the Secret Service Agents and Oswald’s mother — to the minor witnesses no one ever heard of, like Bob Dugger, the unfortunate Dallas police sergeant who was posted outside the trauma room where the President was pronounced dead.

In all, he interviewed over 1,000 people. No one else spoke to more people – not even the Warren Commission – and they were all interviewed when their memories were still fresh.

None of this was easy. At least half of the participants showed emotional distress during the interviews. Manchester remarked that in the year 2067 when the tapes of his long interviews with Mrs. Kennedy will be released, people may wonder about the strange sounds around her words. The background noise came from clinking ice in glass after glass of daiquiris that were needed for both interviewee and interviewer to get through the sessions. There are also the constant sounds of matches lighting cigarettes.

Manchester was punctilious. He walked the entire motorcade route in Dallas as well as the funeral route in Washington. He stood in the trauma room at Parkland hospital, and he sat at the window of the School Book Depository imagining the same Marine rifle training that both he and Oswald received in boot camp.

Only two people refused his interview requests. Marina Oswald, the assassin’s widow, would not talk to him, and Lyndon Johnson would answer questions only on paper. Everyone else obliged his request to be interviewed.

“He asked very detailed questions,” Liz Pozen remembers of Manchester’s interview with her in April 1964. “My memory was still very fresh and later, after I read the book, I found him tremendously accurate.”

The book was scheduled to be published in 1968, but because of Manchester’s dogged work and great speed, he boarded a Trailways bus in Middletown, Connecticut, for New York City on March 25, 1966, carrying carried three copies of the manuscript for the publisher and one each for Jacqueline and Robert Kennedy. The case weighed 77 pounds.

“It was the only time I have had to pay an excess-baggage fee for a bus.” Manchester later recalled.

Instead of a completion of sorts, that turned out to be when his problems began. Manchester needed the approval of both Kennedys, but neither of them could read it. The subject matter was still too painful for them. Instead, they appointed surrogate readers – Kennedy aides Ed Guthman, John Seigenthaler, Richard Goodwin, and Arthur Schlesinger.

The first reactions were more than just positive. Editor Evan Thomas said it the finest book he’d read in 20 years. Schlesinger called it “a remarkable and potentially a great book.”

Manchester worked on the edits that came back to him. All seemed to be going well especially after Robert Kennedy sent him a telegram telling him that the Kennedy family “will place no obstacle in the way of publication of his work.”

Then the issue of the magazine serial rights came up. In a bidding war between Life an Look Magazines, Look won with record breaking $665,000. That should have been cause for celebration.

Instead, Jackie Kennedy took umbrage because all of the money would go to Manchester. She found it unseemly that that anyone should profit from such a painful event.

In truth, while she wanted the history recorded, she really didn’t want anyone to see it.

“I thought that it would be bound in black and put away on dark library shelves.” She later admitted.

Her mistake came in her choice of authors. Manchester had written a book that could not be put down.

But the former first lady would not budge and drew her brother-in-law into the fight. Bobby retracted his telegram. The surrogate editors started to find greater fault with the manuscript. The edits going back to Manchester multiplied. Now, he was even hearing literary criticism from Mrs. Kennedy’s secretary, Pam Turnure, who was weighing in with her thoughts.

Even though Manchester agreed to dozens of edits and revisions, an injunction was filed in a Manhattan Court at the end of 1966 on behalf of Mrs. Kennedy to stop the publication of the book.

Then the fight went to the press with front page headlines. Here, Manchester was overwhelmed. Mrs. Kennedy retained the top lawyers in the country. Even in the publicity war, Manchester acknowledged that although no one would talk directly to the press, all of the Kennedy people had spokesmen. Even the Kennedy spokesmen had spokesmen.

But Manchester’s Marine Corps training never taught him how to surrender and he knew, in spite of everything being said, that he had written an honest, fair and historically accurate book. The quiet author turned out be as dogged as his opposition.

The trial was scheduled to start in January of 1967 with Robert Kennedy as its first witness. But before that ever took place, polls began to show a slippage of positive feelings towards the Kennedys. Realizing the public fight could backfire on the Senator’s possible run for president an out-of-court settlement was negotiated.

The Kennedys’ main upset centered around Manchester’s description of the plane ride back from Dallas that carried the newly sworn-in Lyndon Johnson as well as the body of the late president. To say there was tension between the Kennedy and Johnson people is putting it mildly. JFK’s acting press secretary, Mac Kilduff called it “the sickest plane I’ve ever been on.”

People divided up between loyalists and realists. Everyone was understandably in shock but constitutionally the transfer of leadership is quite clear. Many of the Kennedy aides looked down on Johnson and found it hard to accept that their leader was suddenly gone and this man was now in his place.

Manchester made more changes and the text was eventually cut almost in half. But he would not change his account of the flight back from Dallas because he believed it to be accurate.

“The Death Of A President” was published on April 7, 1967, and became an instant best seller. Over a million copies were sold within months. Look magazine’s issues disappeared quickly from the newsstands.

The fact that the controversy, which preceded publication, disappeared almost overnight is testament to the book’s success. The writer Jerzy Kosinski may have put it best when he told Manchester that “the book’s greatest value was its duality: the way it described events and, simultaneously, how people responded to them.”

“Something like this should have been done after Lincoln’s death,” Dwight Eisenhower told the author. “Then we’d have it now.”

For his part, Manchester was a gentleman throughout. Even though Jacqueline Kennedy put him through an additional amount of torment — not to mention personal legal fees of $100,000 — he was always gracious and understanding of her suffering. He would even campaign for Bobby Kennedy during his truncated run for president in 1968.

Manchester once remarked with some irony that he may have been the largest single donor to the Kennedy Library without his name on the wall. Over one million dollars went to the Library by the end of 1969 from Harper & Row.

“So there were no stalwarts in the controversy, there were no villains either.” Manchester wrote. “The only villain lay in a Texas grave.”

There was some vindication. Manchester was later told that when Jacqueline Kennedy finally brought herself to pick up the book, she was unable to put it down. Her one word response when she finished, closing the cover was “fascinating.”

Finally, after all this time, what are we left with? In his 1967 book review for the New York Times, Eliot Fremont-Smith wrote that “‘The Death Of A President’ cannot be a definitive work. It is too close to the event and, whether or not one approves, parts of it are still continuing.”

The great irony is that Manchester’s book, because of its proximity to the event as well as its tremendous access, stands today as the definitive work. No other book or future book could match this authority. The parts that Fremont-Smith alludes to that were continuing – and never seem to end – are the bizarre conspiracy theories which seem to get stranger with each passing year.

There is one more aspect of the book that makes it unique. Although all readers know the event and the outcome before they pick it up, it still reads like a heart stopping thriller. Rarely has any writer had the ability to write non-fiction in such an intense manner. This is in part due to his collection of thousands of tiny details that are both fascinating and relevant to the story.

Liz Pozen is a perfect example. Although she was closer to the event than most people, she was also every mother in America that weekend. Besides dealing with her own grief she had to explain to a six-year-old why the father of her best friend, a man she often saw at her school, had been killed.

“I still can’t look at the pictures from that time,” she admits, “without my eyes welling up with tears.”

It is precisely because of Manchester’s attention to the smallest detail that we find out one more story about Liz that has a bearing on American history. Earlier that year, she had taken Agatha and Caroline to visit the Custis-Lee Mansion at Arlington Cemetery. Caroline was so enamored with it that she told her father he should visit.

The President was intrigued and one evening around sunset, Kennedy stood not far from where he would be laid to rest just a few months later. Marveling at the view, he murmured, “I could stay here forever.”

Mr. Kozak is the author of LeMay: The Life and Wars of General Curtis LeMay(Regnery, 2009) and the eBook Presidential Courage: Three Speeches That Changed America (2012)