A boy looks back while he and another boy play on a Syrian military tank, destroyed during fighting with the Rebels, in the Syrian town of Azaz, on the outskirts of Aleppo, Sunday, September 2, 2012. (Photo by Muhammed Muheisen/AP Photo)

Russian soldiers write home while serving on the Eastern Front during World War I, circa 1915. (Photo by Hulton Archive/Getty Images)

The last American military convoy to depart Iraq from the 3rd Brigade, 1st Cavalry Division crosses over the border into Kuwait on December 18, 2011 in Khabari Al Awazeem, Kuwait. (Photo by Mario Tama/Getty Images)

Lance Cpl. Blas Trevino of the 1st Battalion, 5th Marines, shouts out as he is rescued on a medevac helicopter from the U.S. Army's Task Force Lift “Dust Off”, Charlie Company 1-214 Aviation Regiment after he got shot in the stomach outside Sangin, in the Helmand Province of southern Afghanistan on June 11, 2011. The Army's 'Dust Off' crew needed two attempts to get him out, as they were fired upon and took five rounds of bullets into the tail of their aircraft. (Photo by Anja Niedringhaus/AP Photo/File)

Mary Pickford takes a picture of husband Douglas Fairbanks, Sr., who is executing a handstand on the roof of a building on December 19, 1920. (Photo by Bettmann Archive/Getty Images)

Shannon Courtenay exchanges punches with Buchra El Quaissi during the Bantamweight between Shannon Courtenay and Buchra El Quaissi at York Hall on December 19, 2019 in London, England. (Photo by James Chance/Getty Images)

A model performs on the catwalk of the Lambertz Monday Night event at Alter Wartesaal in Cologne, Germany, 03 February 2020. (Photo by Friedemann Vogel/EPA/EFE)

Miguel Toribio, 11, puts a pistol belonging to his father into his belt, before demonstrating newly learnt skills from military-style weapons training, to a Reuters journalist in Ayahualtempa, Mexico, February 3, 2020. (Photo by Alexandre Meneghini/Reuters)