Though perhaps best known today as the film that beat Citizen Kane for the Academy Award for Best Picture, How Green Was My Valley was a tremendous hit upon its release (with $6 million in domestic grosses it was 20th Century-Fox's top-grossing film of the year and second only to Sergeant York overall) and remains a beloved classic for its depiction of childhood memories and loss of innocence.

The film focuses on a South Wales mining town at the turn of the century as recalled by Huw Morgan, whose voice-overs as an adult (he's barely seen on-screen) paint a picture of the idyllic community of his youth. Younger Huw (Roddy McDowall) is the youngest son of the large Morgan family that includes his five brothers and older sister Angharad (Maureen O'Hara)--with his father and older brothers all working in the mine. The family is a key part of the community, but though the valley is presented as an idyllic one, change is coming to their beloved home. The film focuses on episodes that reveal why members of the family left the valley and how Huw eventually came to realize that his childhood was over. These episodes include a 22 week miners strike and his sister's ill-fated love for the town's minister (played by Walter Pidgeon).

The film is based on a 1939 novel of the same name by Richard Llewellyn, in which a man named Huw Morgan recounts his childhood in a Welsh mining town. The novel was an immediate hit in England and America, and 20th Century-Fox studio head Darryl F. Zanuck quickly acquired film rights to the novel for $300,000. His vision was to create a film to rival Gone With the Wind (1939), with plans to make it into a 4-hour epic to be shot on location in Wales. Director William Wyler was brought in to bring the novel to the screen, and Laurence Olivier, Katharine Hepburn and Tyrone Power were all on the short list to star in the film.

By the time they were ready to film, however, location shooting had moved to Southern California--the reasons for the move based on both the reduction of the film's budget but also the Nazi bombings of England during this time. Cuts to the budget also led to Wyler, a notorious perfectionist, being taken off the film in favor of John Ford. Wyler would go on to direct the critically acclaimed The Little Foxes (1941).

With Ford on board, the production quickly moved forward--it was his usual practice to shoot only what was eventually going to end up in the film, so that he rarely shot more than three takes of any scene. He also brought in many actors, like Maureen O'Hara and Anna Lee, who would eventually become part of the Ford players (a regular group of actors who frequently appeared in his films).

Upon release, the film was a hit with audiences and critics alike. It would bring Ford the third of his four Best Director Oscars and, of course, win Best Picture for the year. According to Ford biographer Scott Eyman in his book Print the Legend, "Thirty years later, Andrew Sarris maintained that while How Green Was My Valley would not have gotten his vote over Citizen Kane, it was still, Sunrise [1927] excepted, the best film ever to win the Best Picture Oscar."