Tank crew standing in front of M-4 tank, Ft. Knox, Kentucky, June, 1942. (Alfred Palmer/OWI/LOC)

Turkana tribesmen walk with guns to protect their cattle from rival tribes near Baragoy, Kenya August 4, 2017. (Photo by Goran Tomasevic/Reuters)

Members of the Russian Red Army Choir perform at Water Front Theatre in Beirut September 13, 2014. (Photo by Jamal Saidi/Reuters)

Philadelphia Phillies Ben Francisco reacts after being hit in the head with a pitch by Cincinnati Reds Logan Ondrusek during the MLB National League Division Series baseball playoffs in Philadelphia, Pennsylvania, United States in this October 8, 2010 file photo. (Photo by Tim Shaffer/Reuters)

A ballet dancer attends a photo shooting as activists from the environmentalist group Greenpeace unfurl a giant banner on the Eiffel Tower which reads “Liberty, Equality, Fraternity” in a call on French citizens to vote against the National Front (FN) presidential candidate Marine Le Pen, in Paris, France May 5, 2017. (Photo by Gonzalo Fuentes/Reuters)

Argentine Juan Manuel Silva and Pablo Sisterna (not pictured) crash in their Mercedes car during the 7th stage of the Dakar Rally from Iquique to Uyuni, January 10, 2015. (Photo by Daniel Rodrigo/Reuters)

Body builders preparing at the backstage during the Bodybuilding Cup in Kiev, Ukraine on November 7, 2015 which includes classic bodybuilding, physicist and body fitness and bikini in the competition. (Photo by Nazar Furyk/Pacific Press)

Actors dressed up as zombies walk around while posing for photos with passers-by in New York's Times Square on Friday, October 10, 2014 as a promotion for the season premiere of AMC's “The Walking Dead” this Sunday, October 12, 2014. (Photo by Gordon Donovan)