Question: Shakespeare's character Macbeth is based on a historical figure that became King in what year?

Context articles: Macbeth (character)
Lionel Charles Knights
Macbeth, King of Scotland
Atia of the Julii
Three Witches
King Duncan
Harper &amp; Row v. Nation Enterprises
Banquo
Malcolm (Macbeth)
Macbeth (1971 film)

Lord Macbeth, the Thane of Glamis, is the title character and titular main protagonist turned primary antagonist of William Shakespeare's "Macbeth" (c. 1603–1607).
 The character is based on the historical king Macbeth of Scotland, and is derived largely from the account in "Holinshed's Chronicles" (1587), a history of Britain.
Lionel Charles Knights (15 May 1906 – 8 March 1997) was an English literary critic, an authority on Shakespeare and his period.
 His essay "How many children had Lady Macbeth?"
 (1933) is a classic of modern criticism.
 He became King Edward VII Professor of English Literature at the University of Cambridge in 1965.
Macbeth (nicknamed "Rí Deircc ", "the Red King";  1005 – 15 August 1057) was King of Scots from 1040 until his death.
 He was titled King of Alba during his life, and ruled only over a portion of present-day Scotland.
Atia of the Julii is a character from the HBO/BBC/RAI original television series "Rome", played by Polly Walker from 2005 to 2007.
 The niece of Julius Caesar and mother of Octavian/Augustus and Octavia, she is depicted as a cheerfully amoral and opportunistic manipulator whose family connections and sexual liaisons have made her a highly influential figure in Roman society.
 Atia is loosely based on the historical figure Atia Balba Caesonia.
 "Rome" Historical Consultant Jonathan Stamp has said that the character was based on more well-known Roman women of the period, like Clodia.
The Three Witches or Weird Sisters or Wayward Sisters are characters in William Shakespeare's play "Macbeth" (c. 1603–1607).
 They hold a striking resemblance to the three "Fates" (in Greek mythology), and are, perhaps, intended as a twisted version of the white-robed incarnations of destiny.
 The witches eventually lead Macbeth to his demise.
 Their origin lies in "Holinshed's Chronicles" (1587), a history of England, Scotland and Ireland.
 Other possible sources, aside from Shakespeare's imagination itself, include British folklore, such contemporary treatises on witchcraft as King James VI of Scotland's "Daemonologie", the Norns of Norse mythology, and ancient classical myths of the Fates: the Greek Moirai and the Roman Parcae.
 Productions of "Macbeth" began incorporating portions of Thomas Middleton's contemporaneous play, "The Witch", "circa" 1618, two years after Shakespeare's death.
King Duncan is a fictional character in Shakespeare's "Macbeth."
 He is the father of two youthful sons (Malcolm and Donalbain), and the victim of a well-plotted regicide in a power grab by his trusted captain Macbeth.
 The origin of the character lies in a narrative of the historical Donnchad mac Crinain, King of Scots, in Raphael Holinshed's 1587 "The Chronicles of England, Scotland, and Ireland," a history of Britain familiar to Shakespeare and his contemporaries.
 Unlike Holinshed's incompetent King Duncan (who is credited in the narrative with a "feeble and slothful administration"), Shakespeare's King Duncan is crafted as a sensitive, insightful, and generous father-figure whose murder grieves Scotland and is accounted the cause of turmoil in the natural world.
Harper & Row v. Nation Enterprises, 471 U.S. 539 (1985), was a United States Supreme Court decision in which public interest in learning about a historical figure’s impressions of a historic event was held not to be sufficient to show fair use of material otherwise protected by copyright.
 Defendant, "The Nation", had summarized and quoted substantially from "A Time to Heal", president Gerald Ford's forthcoming memoir of his decision to pardon former president Richard Nixon.
 When Harper & Row, who held the rights to "A Time to Heal", brought suit, "The Nation" asserted that its use of the book was protected under the doctrine of fair use, because of the great public interest in a historical figure’s account of a historic incident.
 The Court rejected this argument holding that the right of first publication was important enough to find in favor of Harper.
Lord Banquo , the Thane of Lochaber, is a character in William Shakespeare's 1606 play "Macbeth".
 In the play, he is at first an ally to Macbeth (both are generals in the King's army) and they are together when they meet the Three Witches.
 After prophesying that Macbeth will become king, the witches tell Banquo that he will not be king himself, but that his descendants will be.
 Later, Macbeth in his lust for power sees Banquo as a threat and has him murdered; Banquo's son, Fleance, escapes.
 Banquo's ghost returns in a later scene, causing Macbeth to react with alarm during a public feast.
Malcolm is a character in William Shakespeare's "Macbeth" (c. 1603–1607).
 The character is based on the historical king Malcolm III of Scotland, and is derived largely from the account in "Holinshed's Chronicles" (1587), a history of Britain.
 He is the elder son of King Duncan, the heir to the throne, and brother to Donalbain.
 In the end, he regains the throne after mustering support to overthrow Macbeth.
Macbeth (or The Tragedy of Macbeth) is a 1971 British-American historical drama film directed by Roman Polanski and co-written by Polanski and Kenneth Tynan.
 A film adaptation of William Shakespeare's tragedy of the same name, it retells the story of the Highland lord who becomes King of Scotland through treachery and murder.
 The film stars Jon Finch as the title character and Francesca Annis as Lady Macbeth, noted for their relative youth as actors.
 Themes of historic recurrence, greater pessimism and internal ugliness in physically beautiful characters are added to Shakespeare's story of moral decline, which is presented in a more realistic style.