A member of the mainly Christian “anti-balaka” (anti-machete) militia trains in the Boeing neighbourhood of Bangui, Central African Republic, on February 24, 2014. (Photo by Fred Dufour/AFP Photo)
A female member of the Ahbab Al-Mustafa Battalion holds a gun as she undergoes military training in Aleppo's Salaheddine district, June 24, 2013. (Photo by Muzaffar Salman/Reuters)
Chinese special policemen rank in a line of battle during an anti-terror drill at a training base of Chengdu Armed Police Headquarters on September 28, 2005 in Chengdu of Sichuan Province, China. (Photo by China Photos/Getty Images)
Londoners sleep on the platform and on the train tracks at Aldwych Underground station,London, during heavy all night Nazi bombing raids, October 8, 1940. (Photo by AP Photo)
A rag-and-bone woman stands next to carriages of a coal train outside a coal mine of the state-owned Longmay Group on the outskirts of Jixi, in Heilongjiang province, China, October 22, 2015. (Photo by Jason Lee/Reuters)