Revellers dressed in mock military garb take part in the “Els Enfarinats” battle in the southeastern Spanish town of Ibi on December 28, 2017. During this 200-year-old traditional festival participants known as Els Enfarinats (those covered in flour) dress in military clothes and stage a mock coup d'etat as they battle using flour, eggs and firecrackers outside the town hall as part of the celebrations of the Day of the Innocents. (Photo by Jaime Reina/AFP Photo)

A US Marine leads two Viet Cong suspects in restraints during the Tet Offensive on February 20, 1967. (Photo by Bettmann Archive/Getty Images)

Medic James E. Callahan of Pittsfield, Mass., gives mouth-to-mouth resuscitation to a dying soldier in war zone D, about 50 miles northeast of Saigon, June 17, 1967. Thirty-one men of the 1st Infantry Division were reported killed in the guerrilla ambush, with more than 100 wounded. (Photo by Henri Huet/AP Photo)

Military enthusiasts take part in a re-enactment of the World War II battle of Stalingrad at the “Stalin Line” memorial, near the village of Goroshki, Belarus, February 27, 2016. (Photo by Vasily Fedosenko/Reuters)

A man yells for help minutes after a Serb shell hit a crowded pedestrian walkway in Sarajevo, May 1993. Radovan Karadzic, a 70-year-old former psychiatrist, still in robust health, is the most senior political figure to be convicted by the International Criminal Tribunal for the Former Yugoslavia. He was found guilty of 10 out of 11 charges. He was acquitted of a second count of genocide in Bosnian towns. (Photo by Reuters)

An interactive art installation created by artist Michael Verdon called the “Temple of Essence” dedicated to "victims of the war on drugs" is burned on the U.S. National Mall in front of the Washington Monument in Washington November 22, 2015. People were encouraged to write personal messages on the temple walls and leave mementos behind inside the interactive art piece, which was the centerpiece of a 48-hour vigil called "Catharsis on the Mall: A Vigil for Healing the Drug War". (Photo by Jim Bourg/Reuters)

Audrey Mata from Washington D.C in the U.S. dressed as Princess Leia, comes face to face with a replica of R2-D2 at the 'For The Love of The Force' Star Wars fan convention in Manchester, northern England, December 4, 2015. (Photo by Phil Noble/Reuters)

British soldiers inspect a captured German place in the Horseguards' Parade, London during World War I in November 1914, with the London Eye in the background as a reminder of just how much has changed in the last 100 years. (Photo by Peter Macdiarmid/Getty Images)