A re-enactor poses for a portrait before a re-enactment of the Battle of Hastings, commemorating the 950th anniversary of the battle, in Battle, Britain October 15, 2016. Some thousands of history buffs including many in full costume marked the 1066 Battle of Hastings with a dramatic reenactment that commemorates one of the most important events in British history. (Photo by Neil Hall/Reuters)

People dressed in the historic uniforms of the Imperial Russian army take part in a re-enactment of the 1812 Battle of Berezina, to mark the 204th anniversary of the battle, near the village of Bryli, Belarus, November 27, 2016. (Photo by Vasily Fedosenko/Reuters)

A history enthusiast, dressed as a soldier, marches before the re-enactment of Napoleon's famous battle of Austerlitz near the southern Moravian town of Slavkov u Brna, Czech Republic December 3, 2016. (Photo by David W. Cerny/Reuters)

Gas-masked men of the British Machine Gun Corps with a Vickers machine gun during the first battle of the Somme, 1916. (Photo by General Photographic Agency/Getty Images)

National Geographic invites photographers from around the world to enter the 2013 National Geographic Photography Contest. The grand-prize winner will receive $10,000 (USD) and a trip to National Geographic headquarters in Washington, D.C., to participate in the annual National Geographic Photography Seminar in January 2014. Photo: “We just want to move to search to the Leopard at that morning but we found a group of giraffes come toward a small lake and start drinking it was a nice moment when the Giraffe finish from drinking and leave a letters “S” with motion in the air”. (Photo and caption by Majed Ali/National Geographic Photography Contest)

Turkish Kurds watch the Syrian town of Kobani from near the Mursitpinar border crossing, on the Turkish-Syrian border in the southeastern town of Suruc, October 19, 2014. (Photo by Kai Pfaffenbach/Reuters)

Iraqi pro-government forces fire an anti-tank cannon near al-Sejar village, north-east of Fallujah, on May 25, 2016, as they take part in a major assault to retake the city from the Islamic State (IS) group. Iraqi forces, consisting of special forces, soldiers, police, paramilitary-fighters and pro-government tribesmen, launched a major assault to retake Fallujah, the scene of deadly battles during the US occupation and one of the toughest targets yet in Baghdad's war on the Islamic State group. (Photo by Ahmad Al-Rubaye/AFP Photo)

A competitor scrambles in the mud under barbed wire during the Tough Guy Challenge 2009 at South Perton Farm on February 1, 2009 in Wolverhampton, England. The biannual event to raise cash for charity challenges thousands of international competitors to run through a gruelling set of 21 obstacles including water, fire and tunnels after a lengthy run at the start. (Photo by Christopher Furlong/Getty Images)