A line of soldiers firing handguns during a training session, circa 1920. (Photo by Keystone). P.S. All pictures are presented in high resolution.

A cadet lies on the grass after collapsing during a promotion ceremony at a police school in Bogota December 7, 2012. (Photo by John Vizcaino/Reuters)

Jorge Diaz punches Teon Kennedy during their USBA Super Bantamweight bout during Top Rank's 'Featherweight Fury' on March 26, 2011 at Boardwalk Hall in Atlantic City, New Jersey.

Artists preform on a pool suspended above the audience during the Fuerza Bruta dress rehearsal on February 1, 2012 in Tel Aviv, Israel. (Photo by Uriel Sinai/Getty Images)

Iraqi forces gather during an operation to attack Islamic State militants in Mosul, Iraq, October 21, 2016. (Photo by Reuters/Stringer)

A boat is stranded on Poyang Lake in Lushan City, China during low-water season on November 3, 2016. (Photo by Xinhua/Barcroft Images)

An artist draws a tattoo on a woman's arm during a tattoo convention in Ljubljana April 18, 2015. (Photo by Srdjan Zivulovic/Reuters)

A man arranges a display of cacti during preparations for the RHS Chelsea Flower Show in London, Britain May 21, 2016. (Photo by Neil Hall/Reuters)