Which 1940 John Ford film adapted four Eugene O'Neill plays?

The Long Voyage Home is the 1940 John Ford film adapted from four Eugene O’Neill plays.

Screenwriter Dudley Nichols combined The Moon of the Caribbees, In the Zone, Bound East for Cardiff, and The Long Voyage Home into a single story about sailors aboard a tramp steamer. Although O’Neill wrote the plays around World War I, Ford relocated the film’s setting to the early years of World War II.

The film stars John Wayne, Thomas Mitchell, Ian Hunter, and Barry Fitzgerald, but it is an ensemble drama rather than a conventional star vehicle. The Plough and the Stars is also associated with Irish drama and Ford, which can cause confusion, but it was adapted from Sean O’Casey’s play, not four O’Neill works.