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)

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

A woman and a child walk past the remains of collapsed houses damaged during the April 2015 earthquake, in Bhaktapur, Nepal March 18, 2016. The two devastating earthquakes that struck Nepal last year killed almost 9,000 people across the country. Inside the Kathmandu Valley almost 2,000 died, and some of the area's most important cultural and heritage sites were completely destroyed. As Kathmandu inhabitants prepare to mark the one-year anniversary of the event, thousands are still displaced and millions are living in temporary shelters. (Photo by Navesh Chitrakar/Reuters)

An internally displaced woman collects water from a pond to construct a mud-house at the Aboushok camp in El Fasher, North Darfur, Sudan, November 17, 2015. The conflict in Sudan's Darfur region that erupted 12 years ago shows no sign of ending. But it hasn't stopped displaced youngsters, some of whom have spent their entire lives in refugee camps, from dreaming big. Twelve children aged 12 explain their hopes and dreams for the future; ambitions include becoming a doctor, an engineer and a teacher. (Photo by Mohamed Nureldin Abdallah/Reuters)

Baraa Melhem plays on her sisters bike at her mothers house on February 2, 2012 in Qalandia, near Ramallah, West Bank. Baraa Melhem was held in captivity in a bathroom by her father for over nine years, and was finally rescued by Palestinian security forces after a family member notified police. (Photo by Ilia Yefimovich/Getty Images)

A recruitment drive during the First World War at Trafalgar Square, London. (Photo by Central Press/Getty Images)

German field telegraph operators at work in Warsaw. (Photo by Hulton Archive/Getty Images). 1st October 1914

A visitor poses for a picture during Sao Paulo Fashion Week in Sao Paulo, Brazil, March 16, 2017. (Photo by Nacho Doce/Reuters)