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

Israeli soldiers get ready to launch the Skylark drone during a drill on January 16, 2012 near Bat Shlomo, Israel. (Photo by Uriel Sinai/Getty Images)

In this Sunday, May 29, 2016 photo, fighters take a selfie while firing artillery during fight against Islamic State militants in Fallujah, Iraq. Iraqi forces this week pushed into the city's southern sections after securing surrounding towns and villages more than 50,000 people are believed to be trapped inside the Sunni majority city, about 65 kilometers (40 miles) west of Baghdad. (Photo by Anmar Khalil/AP Photo)

A Myanmar Shiite Muslim devotee runs barefoot over a bed of burning coals as he takes part in a Muharram procession ahead of the Islamic holiday Ashura, in Yangon, Myanmar, October 22, 2015. Muslims across the world are observing Moharram, the first month of Islamic calender, the climax of Moharram is the Ashura festival commemorating the martyrdom of Imam Hussein, a grandson of the Prophet Mohammed in the Iraqi city of Karbala in the seventh century. (Lynn Bo Bo/EPA)

Iraqi Kurds carry fire torches as they celebrate Nowruz Day, a festival marking the first day of spring, Kurdish and Persian New Year in Akre, Iraq on March 20, 2024. Newroz or Nowruz means “new day” in Persian, and is celebrated to mark the arrival of spring and the first day of the Iranian calendar. It is widely celebrated in Persian and neighboring regions and is recognized on UNESCO's Intangible Cultural Heritage of Human List. (Photo by Ismael Adnan/SOPA Images/Rex Features/Shutterstock)

Soldiers, including two recruits who have brought some chickens, at Victoria prepare to board the train for the battle front. (Photo by Hulton Archive/Getty Images)

A South Sudanese People Liberation Army (SPLA) soldier patrols the streets in Malakal on January 21, 2014. (Photo by Harrison Ngethi/AFP Photo)

Soldiers try to attach the balloon to their car, June 1944. (Photo by Jared Enos/Mediadrumworld.com)