Members of the American Civil War Society take part in a mock battle in the grounds of Cusworth Hall, South Yorkshire on July 2, 2011 in Doncaster, United Kingdom. Enthusiasts from all walks of life are taking part in re-enacting scenes from the American Civil War and in 'living history' events which are as authentic as possible. (Photo by Christopher Furlong/Getty Images)

Encyclopedia Britannica editions are seen at the New York Public Library on March 14, 2012 in New York City. Encyclopedia Britannica announced it will be ceasing its print edition of reference books for the first time in its 244-year history to focus solely on digital versions. (Photo by Mario Tama/Getty Images)

The X-47B prototype on Tuesday flew off an aircraft carrier and into the history books. Today's achievement, the first-ever catapult launch of an unmanned aircraft from the flight deck of a carrier, promises to open up a new chapter in the annals of naval aviation. Photo: An X-47B pilot-less drone combat aircraft is launched for the first time off an aircraft carrier, the USS George H. W. Bush, in the Atlantic Ocean off the coast of Virginia, May 14, 2013. The U.S. Navy made aviation history on Tuesday by catapulting an unmanned jet off an aircraft carrier for the first time, testing a long-range, stealthy, bat-winged plane that represents a jump forward in drone technology. (Photo by Jason Reed/Reuters)

A man takes part in Belarus Wakeboard Cup in Minsk, Belarus June 18, 2016. (Photo by Vasily Fedosenko/Reuters)

History enthusiasts of French association “Arquebusiers de l'Est”, dressed as soldiers of 3rd regiment of Zouave, attend an Armistice Day ceremony to commemorate the end of World War One at Epernay, eastern France, November 11, 2014. More than a hundred volunteers from France, Romania, England, Belgium, Russia and Italy took part in the parade. The year 2014 marks the centennial commemoration for the soldiers who fought in the First World War (WWI). (Photo by Charles Platiau/Reuters)

A lightning strikes St Peter's dome at the Vatican on February 11, 2013. Pope Benedict XVI announced today he will resign as leader of the world's 1.1 billion Catholics on February 28 because his age prevented him from carrying out his duties – an unprecedented move in the modern history of the Catholic Church. (Photo by Filippo Monteforte/AFP Photo)

An undercover police officer, who had been marching with anti-police demonstrators, aims his gun at protesters after some in the crowd attacked him and his partner in Oakland, California December 10, 2014. Police said more than 100 demonstrators marched in Berkeley, California, which has a history of social activism. Under cloudy skies, turnout was smaller than earlier in the week, when demonstrators in the area threw rocks at police and shut down a major freeway. (Photo by Noah Berger/Reuters)

Supporters of the presidential candidate Muhammadu Buhari and his All Progressive Congress hits with a motorbike another supporter during celebrations in Kano March 31, 2015. Nigeria's opposition APC declared an election victory on Tuesday for former military ruler Buhari and said Africa's most populous nation was witnessing history with its first democratic transfer of power. (Photo by Goran Tomasevic/Reuters)