When President John F. Kennedy was assassinated in 1963, 1.5 million condolence letters were sent to his young widow by citizens from all walks of life.

Now a new documentary called Letters To Jackie, set to air in the fall, will gives voice to some of the letters received as the 50 anniversary of the Dallas shooting approaches on November 22.

Stars who will lend their voices to the private letters include Jessica Chastain, Anne Hathaway and Michelle Williams.

The documentary is based on the book, Letters To Jackie: Condolences from a Grieving Nation, by Ellen Fitzpatrick, and it will focus on the first lady as she steels her way through her grief, and that of the nations, attempting to steady her two children in the aftermath of the tragedy.

Describing what inspired the movie, filmmaker Bill Couturie told the Daily Mail: 'I'll never forget where I was when JFK was killed. No one will. It cast a dark shadow over America.

'Afterwards, the American people poured out their hearts to Jackie. The strength and wisdom of the nation, coming out of profound tragedy, rings clear in these letters. As soon as I read them, I knew I had to make a movie around them and the time they so eloquently evoke.'

Fitzpatrick's book, published in 2010, revealed a selection of letters to the First Lady for the first time.

The White House reportedly received 1.5 million letters and words of comfort in the two months after Kennedy's death, with 45,000 arriving on one day alone.

Among the envelopes was a letter from Jane Dryden, an 11-year-old who wrote: 'I know that you hate the whole state of Texas. I do too,' she wrote from the state's capital Austin. 'I wish I lived in Washington, D.C. I would feel safer there.'

Given the overwhelming volume of post received, much of it was destroyed shortly after it arrived. But 200,000 pages were sent to the John F. Kennedy Library in Boston where they lay forgotten until historian Fitzpatrick put a selection of them into her book.

Larry Toomey of Upper Darby, Pennsylvania, couldn't wait for official confirmation of Kennedy's death before starting his letter.

'My dear Mrs Kennedy, even as I write this letter, my hand, my body is trembling at the terrible incident of this afternoon. I am watching the CBS-TV news report. No official word as yet.'

Fitzpatrick was reportedly at the Kennedy library researching a book when, out of curiosity, she asked to see some of the condolence letters in hopes of getting a sense of how Kennedy was perceived by Americans in his own time. Right away she was hooked.

'It was like the roof came off the building, the walls dropped away, the floor came out from under me. I was absolutely floored by what I'd begun to read,' she said.

'I have been teaching American history for 30 years, and I'm not sure I've ever seen a collection as powerful and that represented so many ordinary people speaking from the heart about their views about American society, and politics, and the president.'

Fitzpatrick, a University of New Hampshire professor, whittled down her list of favorites from 3,000 to 240, only five of the 220 and managed to track down relatives of the letter writers.

One of the shortest letters came from Martin Rosenberg, a student at the University of Massachusetts who wrote: 'Dear Mrs Kennedy: I have never seen our football players cry, but today, they did.'

Jackie Kennedy - after President John F. Kennedy assassinated in 1963, 1.5 million condolence letters were sent to his young widow by citizens from all walks of life.Google Images