100 years on
A hundred years have passed since the beginning of World War One, which ravaged much of Europe, especially northern France and Belgium, and killed some 17 million people from countries across the globe.
The conflict ushered in the modern era of warfare with a wide range of military and technological “firsts”, from the invention of the tank, to major developments in military aircraft.
Aircraft carriers like the British HMS Argus, pictured above, were used for the first time during the First World War. The ship is painted with wartime "dazzle" camouflage.
Observation balloons had been part of warfare long before World War One, but the conflict saw them put to very wide use. Here, an American World War One observation balloon is held by ropes.
The war also witnessed major developments in the use of military aircraft. In the image above, 1st Lt. Eddie Rickenbacker, America's most successful World War One fighting ace, stands next to a biplane.
During the war, steel helmets were used for the first time as protective headgear for soldiers. Here, U.S. members of the 1st Division advance to seize and hold Cantigny in France.
World War One was also the first major conflict where a majority of casualties were inflicted by artillery. In this image, U.S. artillerymen fire a 75mm gun toward Montsec from a position near Beaumont.
Mobile X-rays were developed during the war to aid doctors in performing battlefield surgeries. A Renault truck fitted out with mobile X-ray equipment is seen here.
After the end of the First World War, Woodrow Wilson came to France for peace negotiations, becoming the first U.S. president to make an official trip to Europe. In this image, Wilson and French President Raymond Poincare ride together through Paris.
The “Big Four” Allied leaders of World War One (left-right) British Prime Minister David Lloyd George, Italian Premier Vittorio Emanuele Orlando, French Premier Georges Clemenceau and U.S. President Woodrow Wilson are seen in Versailles at the Paris Peace Conference.
The first officially enlisted women appeared in the U.S. military in World War One, when the Navy created a reserve force which allowed women to work as yeomen, radio operators, nurses, or in other support roles. In this 1918 image, Rear Adm. Victor Blue inspects female yeomen on the grounds of the Washington Monument.
German soldiers sit in a dugout, with a soldier on the left using a field telephone. During World War One, field telephones and wireless communications were regularly used for the first time to coordinate military movements.
Chemical weapons in the form of deadly poison gases were also employed in the war, leading quickly to the development of countermeasures like the first gas masks. In this photo, which was probably used for training purposes, five U.S. soldiers wear gas masks while another clutches his throat.
The destroyed town of Passchendaele is seen from an aerial reconnaissance photograph during World War One.
