Two guards perform an execution in China, one holding the gun, the other holding a mask over the victim's face. (Photo by General Photographic Agency/Getty Images). Circa 1925

A dejected German Grenadier carrying a machine gun on his shoulder in front of a building on fire during the German retreat in Russia. (Photo by Keystone/Getty Images). 1944

A Russian trenchmortar crew run to take up a new firing position in the Stalingrad area during the Great Patriotic War. (Photo by Keystone/Getty Images). October 1942

A young lady blows a balloon during a federal conference of the German Pirate Party (Piratenpartei) on December 3, 2011 in Offenbach, Germany. (Photo by Ralph Orlowski/Getty Images)

South Korean police officers show their martial arts' skills during the official launch ceremony of the 2012 Seoul Nuclear Security Summit on February 15, 2012 in Seoul, South Korea. The Korean National Police Agency launched a security squad, exclusively established for the successful hosting of the 2012 Seoul Nuclear Security Summit. The 2012 Seoul Nuclear Security Summit will be held in Seoul from March 26-27, 2012. (Photo by Chung Sung-Jun/Getty Images)

A TV journalist reports next to a life-size cutout of Pope Francis outside the Catholic Nunciature before the pontiff arrives in Mexico City, Friday, February 12, 2016. Pope Francis is arriving in Mexico on Friday for a week-long visit. (Photo by Christian Palma/AP Photo)

Mrs. Marie Graskamp of Milwaukee shows the different positions one might assume when entering the bomb shelter in Milwaukee September 3, 1958. This circular entrance is about three feet in diameter. This is the entrance (according to the builders) that would connect to the cellar of a home assuming the shelter was in the ground for added protection. If a bombing should occur, all members of family would proceed to the cellar and then through the circular port into the shelter. (Photo by AP Photo)

American film director Mike Todd and his actress wife Elizabeth Taylor get into a spat after missing their flight from London to Nice on June 22, 1957. (Photo by AP Photo)