Do you want a US history lesson? Look no further than the frontrunners for the best film Academy Award, announced Thursday. Nearly half the movies nominated for best picture Oscar are about key events in America\'s past, from the abolition of slavery to the post 9/11 hunt for Osama bin Laden. Steven Spielberg\'s drama \"Lincoln\" could also offer a lesson to current US politicians, as the 16th US president schemed to get bipartisan support in Congress. Slavery and the American Civil War era also provide the backdrop for Quentin Tarantino\'s latest blood-fest \"Django Unchained,\" about a slave-turned-bounty hunter seeking to free his wife from Leonardo DiCaprio\'s clutches. Historical accuracy is not necessarily guaranteed: \"Argo\" allegedly takes liberties with facts about the 1979 Iran hostage crisis, and the CIA has blasted the depiction of torture in the bin Laden flick \"Zero Dark Thirty.\" Spielberg\'s latest movie, which led the field with nominations in 12 categories, tells the story of Abraham Lincoln\'s drive to secure crucial votes to pass the 13th Amendment, which abolished slavery in the United States. Played with uncanny realism by Daniel Day-Lewis -- frontrunner for best actor -- the Republican president stops at little beyond outright financial bribery to twist Democrats arms into backing the constitutional amendment. Non-Americans might learn a thing or two as well: that it was the Democrats who opposed abolition seems surprising from the modern point of view, as are the political machinations which eventually ended the Civil War. \"Django Unchained\" is set a few years before the Civil War, when Jamie Foxx\'s title character is freed by a wandering German dentist turned bounty hunter, embarking on a killing spree typical of the \"Pulp Fiction\" director. Tarantino justifies the relentless use of the \"N\" word as historically accurate, but that hasn\'t stopped critics slamming it for linguistic exaggeration, as well as shooting overload, notably after last month\'s school massacre. Ben Affleck\'s Iran hostage crisis drama \"Argo\" tells the story of a CIA agent -- played by the actor-director himself -- bidding to free six US diplomats who take refuge in the Canadian ambassador\'s residence in Tehran. Critics have included then Canadian envoy Ken Taylor, depicted as playing a clearly supporting role in the plot to get them out of the country disguised as a Canadian film crew. \"The movie\'s fun, it\'s thrilling, it\'s pertinent, it\'s timely,\" Taylor told Canada\'s Star newspaper recently. \"But look, Canada was not merely standing around watching events take place. The CIA was a junior partner.\" Oscar-winning director Kathryn Bigelow\'s \"Zero Dark Thirty\" also focuses on a CIA agent: the female one credited with tracking down bin Laden\'s hideout in Pakistan, where US special forces killed him in May 2011. The movie includes graphic scenes of so-called \"enhanced interrogation techniques,\" widely seen as torture, and portrays their role in pinpointing the Al-Qaeda\'s chief\'s courier who eventually led to his compound in Abbottabad. That has earned it criticism from lawmakers including former presidential candidate John McCain and from acting CIA chief Michael Morell, claiming the film exaggerates the importance of information obtained by such techniques. A rights group joined those voicing concern Thursday, after the movie\'s Oscar nomination. The Center for Constitutional Rights said it was \"profoundly disappointed to see that Hollywood is prepared to bestow its highest honor upon a film that glorifies one of the darkest periods in our nation\'s history. \"This should be a moment of national shame and a commitment never to repeat the horrors depicted in the film ... We hope that members of the Academy will vote their consciences and withhold their votes from this film,\" it said.