Question: What star of Silver River became a U.S. citizen in 1942?

full_context: Document 1: Long John Silver (film): Long John Silver, also known as Long John Silver's Return to Treasure Island, is a 1954 American-Australian Adventure film about the eponymous pirate from "Treasure Island", starring Robert Newton as Silver and Rod Taylor as Israel Hands.
Document 2: Olivia de Havilland: Dame Olivia Mary de Havilland, {'1': ", '2': ", '3': ", '4': "} ( ; born July 1, 1916) is a retired American actress. Her career spanned from 1935 to 1988. She appeared in 49 feature films, and was one of the leading movie stars during the golden age of Classical Hollywood. She is best known for her early screen performances in "The Adventures of Robin Hood" (1938) and "Gone with the Wind" (1939), and her later award-winning performances in "To Each His Own" (1946), "The Snake Pit" (1948), and "The Heiress" (1949).
Document 3: Silver River (film): Silver River is a 1948 western film directed by Raoul Walsh and starring Errol Flynn and Ann Sheridan. The film is based on a Stephen Longstreet novel.
Document 4: Up the River (1938 film): Up the River (1938) is a prison comedy film starring Preston Foster and Arthur Treacher and featuring Bill "Bojangles" Robinson. The movie was directed by Alfred L. Werker and is a remake of a 1930 film with the same title directed by John Ford and starring Spencer Tracy and Humphrey Bogart in the roles subsequently played by Foster and Tony Martin.
Document 5: Shark River (film): Shark River is a 1953 American Florida Western adventure film directed by John Rawlins and written by Louis Lantz and Lewis Meltzer. It stars Steve Cochran, Carole Mathews, Warren Stevens, Robert Cunningham, Ruth Foreman, Spencer Fox and Bill Piper, and was released on November 13, 1953, by United Artists.
Document 6: Cary Grant: Cary Grant (born Archibald Alec Leach; January 18, 1904 – November 29, 1986) was a British-American actor, known as one of classic Hollywood's definitive leading men. He began a career in Hollywood in the early 1930s, and became known for his transatlantic accent, debonair demeanor, and light-hearted approach to acting and sense of comic timing. He became an American citizen in 1942.
Document 7: Irving Asher: Irving Asher (1903–1985) was an American film producer. Born in San Francisco in September 1903, he began his film production career in Hollywood in 1919. After joining the staff of Warner Brothers he was sent over to England as the managing director of their subsidiary Teddington Studios in Middlesex in the mid 1930s (where he is credited for discovering and seeing the potential of Errol Flynn when he was a young unknown actor who was hanging around Teddington Studios at the time looking for a way into the movies). Flynn played his first significant part as the lead in the now-lost "Murder at Monte Carlo" (1935), which was produced by Asher.
Document 8: Errol Flynn: Errol Leslie Flynn (20 June 1909 – 14 October 1959) was an Australian-born American actor who achieved fame in Hollywood after 1935. He was known for his romantic swashbuckler roles in Hollywood films, as well as frequent partnerships with Olivia de Havilland. He became a U.S. citizen in 1942.
Document 9: The River (1984 film): The River is a 1984 American drama film directed by Mark Rydell, written by Robert Dillon and Julian Barry, and stars Mel Gibson, Sissy Spacek, and Scott Glenn. The film tells the story of a struggling farm family in the Tennessee valley trying to keep its farm from going under in the face of bank foreclosures and floods. The father faces the dilemma of having to work as a strikebreaker in a steel mill to keep his family farm from foreclosure. It was based on the true story of farmers who unknowingly took jobs as strikebreakers at a steel mill after their crops had been destroyed by rain.
Document 10: Nora Eddington: Nora Eddington (February 25, 1924 – April 10, 2001) was an American actress and socialite. She was best known as the second wife of actor Errol Flynn. Eddington was featured as an actress in several minor film roles.
Document 11: Bend of the River: Bend of the River is a 1952 American Technicolor Western film directed by Anthony Mann and starring James Stewart, Arthur Kennedy, Julie Adams, and Rock Hudson. Based on the 1950 novel "Bend of the Snake" by Bill Gulick, the film is about a tough cowboy who risks his life to deliver confiscated supplies to homesteaders after gold is discovered in the region. "Bend of the River" was filmed on location in Sandy River, Mount Hood and Timberline, Oregon. This is the second Western film collaboration between Anthony Mann and James Stewart.
Document 12: River of Romance: River of Romance is a 1929 American drama film directed by Richard Wallace and written by Ethel Doherty, Joseph L. Mankiewicz, Dan Totheroh and John V.A. Weaver. The film stars Charles 'Buddy' Rogers, Mary Brian, June Collyer, Henry B. Walthall, Wallace Beery, Fred Kohler and Natalie Kingston. It is based on the play "Magnolia" by Booth Tarkington. The film was released on June 29, 1929, by Paramount Pictures.
Document 13: The Silver Chalice (film): The Silver Chalice is a 1954 American historical epic film directed and producer by Victor Saville, based on Thomas B. Costain's 1952 novel of the same name. It was Saville's last film and marked the acting debut of Paul Newman; despite being nominated for a Golden Globe Award for his performance, Newman later called it "the worst motion picture produced during the 1950s".
Document 14: Olivia de Havilland filmography: The Olivia de Havilland filmography lists the film appearances of American actress Olivia de Havilland, as well as her television, stage, and radio credits. De Havilland's career spanned fifty-three years, from 1935 to 1988. During that time, she appeared in forty-nine feature films, and was one of the leading movie stars during the golden age of Classical Hollywood. She is best known for her early screen performances in "The Adventures of Robin Hood" (1938) and "Gone with the Wind" (1939), and her later award-winning performances in "To Each His Own" (1946), "The Snake Pit" (1948), and "The Heiress" (1949). De Havilland made her screen debut in Reinhardt's film adaptation "A Midsummer Night's Dream" in 1935. She began her career playing demure ingénues opposite popular leading men of that time, including Errol Flynn, with whom she made her breakout film "Captain Blood" in 1935. They would go on to make seven more feature films together, and became one of Hollywood's most popular romantic on-screen pairings.
Document 15: Tyrone Power: Tyrone Edmund Power III (May 5, 1914 – November 15, 1958) was an American film, stage and radio actor. From the 1930s to the 1950s Power appeared in dozens of films, often in swashbuckler roles or romantic leads. His better-known films include "The Mark of Zorro", "Blood and Sand", "The Black Swan", "Prince of Foxes", "Witness For The Prosecution", "The Black Rose", and "Captain from Castile". Power's own favorite film among those that he starred in was "Nightmare Alley".
ground_truth: Errol Leslie Flynn