An armed man herds his cattle close to the village of Nimini in northern South Sudan, February 8, 2017. In the chaos of South Sudan's civil war, it took three years for Nyagonga Machul to find her lost children. Machul had traveled from her village to the capital when President Salva Kiir, an ethnic Dinka, fired his deputy Riek Machar, a Nuer, in 2013. (Photo by Siegfried Modola/Reuters)

A painting of a Trabant car bursting through a wall in post unification Berlin, August 1993. (Photo by Steve Eason/Hulton Archive/Getty Images)

A nurse consoles herself with a box of chocolates as she reads a paper-back thriller. (Photo by Hulton Archive/Getty Images). Circa 1955

Two dummy tanks being pushed along a road by German soldiers. (Photo by Hulton Archive/Getty Images). Circa 1925

King George V inspects the day's kill after a tiger hunt in India during his royal visit to celebrate his accession to the throne. (Photo by Hulton Archive/Getty Images). 1911

Smithfield meat porters march on the Home Office, bearing a petition which calls for an end to all immigration into Britain, 25th August 1972. (Photo by Keystone/Hulton Archive/Getty Images)

Heavy artillery on parade during a review of the Moscow Garrison troops during the May Day celebrations in Red Square, passing posters of Lenin and Stalin. (Photo by N. Sitnikov/Hulton Archive/Getty Images). 1st May 1947

Pope John Paul II (1920–2005) is shot by would-be assassin Mehmet Ali Agca in St Peter's Square, 13th May 1981. His attendants help him into his white jeep after the incident. (Photo by Keystone/Hulton Archive/Getty Images)