A German rifleman beside the corpse of a French soldier in a trench at Fort Vaux, France, 1916. (Photo by Hulton Archive/Getty Images)

An undated archive picture shows a dog pulling a Belgian machine gun at an unknown location in northern France. A Viscount in the Armoured Cavalry Branch of the French Army left behind a collection of hundreds of glass plates taken during World War One (WWI) that have never before been published. The images, by an unknown photographer, show the daily life of soldiers in the trenches, destruction of towns and military leaders. The year 2014 marks the 100th anniversary of the start of WWI. (Photo by Collection Odette Carrez/Reuters)

Aviation enthusiast Patrick Wilson 8, from Wetherby looks at an Avro 504 k at “The Shuttlesworth Collection” at Old Warden on July 21, 2014 in Biggleswade, England. Of the 55,000 planes that were manufactured by the Royal Army Corps (RAC) during WWI, only around 20 remain in airworthy condition. Six of these belong to The Shuttleworth Collection at Old Warden, Bedfordshire, making it the most complete collection of original airworthy WWI aircraft in the world. Amongst the collection is the SE5a. The SE5a is a single seater fighter aircraft. It is an original biplane designed by the Royal Aircraft Factory, with its engine built by Wolseley Motors Ltd, and it was issued to 84 Squadron in November 1918. The National Archive in Kew has recently verified that the plane saw action in France with 84 Squadron the day before Armistice, November 10, 1918. (Photo by Dan Kitwood/Getty Images)

Fire rises from an oil tank in the port of Es Sider, in Ras Lanuf, Libya January 4, 2016. Firefighters have extinguished two fires at oil storage tanks at Libya's Ras Lanuf terminal, but blazes continue at five tanks in the nearby port of Es Sider after attacks this week by Islamic State militants, a Petroleum Facilities Guards (PFG) spokesman said on Thursday. (Photo by Reuters/Stringer)

A tank's barrel is seen on the course of the Tank Biathlon competition during the International Army Games 2016 in Alabino, outside Moscow, Russia, July 30, 2016. (Photo by Maxim Zmeyev/Reuters)

A portrait of French WWI soldier Edouard Marius Ivaldi is displayed on a tablet, in this illustration picture, alongside his battlefield grave memorial, a wooden cross with a battlefield helmet in Champagne, eastern France, November 3, 2015. (Photo by Charles Platiau/Reuters)

Tank crew standing in front of M-4 tank, Ft. Knox, Kentucky, June, 1942. (Alfred Palmer/OWI/LOC)

A US Army M1A2 SEP tank participates in the Strong Europe Tank Challenge 2017 at the military training area in Grafenwoehr, Germany, 12 May 2017. Six North Atlantic Treaty Organization (NATO) nations and partner nations, Austria, France, Germany, Poland, Ukraine and the USA are taking part in this competing exercise. (Photo by Christian Bruna/EPA)