Although the name "Big Bertha" subsequently came to be applied generically by the Allies to any very large German gun, strictly speaking it is only applicable to the 42-cm M-Gerät howitzer.

During World War I, the Vickers machine gun became a standard weapon on British and French military aircraft. Although heavier than the Lewis, its closed bolt firing cycle made it much easier to synchronize to allow it to fire through aircraft propellers.

By the time soldiers noticed the presence of mustard gas on the battlefield, it was often too late. Fortunately, slugs could detect mustard gas well before humans could. The slugs would visibly indicate their discomfort by closing their breathing pores and compressing their bodies, and soldiers in the trenches would quickly put on their gas masks to protect themselves from harmful levels of gas. The "slug brigade" ended up saving many lives.

The Paris Gun, designed by the Germans to bombard Paris, holds an important place in the history of astronautics, as its shells were the first human-made objects to reach the stratosphere. When the guns were first employed, Parisians believed they had been bombed by a high-altitude Zeppelin, as the sound of neither an airplane nor a gun could be heard.

Colonel René Paul Fonck, a French aviator, was the top Allied fighter pilot with 75 confirmed aerial victories. He was made an Officer of the Legion of Honor in 1918 and later a Commander of the Legion of Honor after the war.

Many Americans were not in favor of the U.S. entering the war and wanted to remain neutral, but on April 6, 1917, the U.S. joined WWI alongside its allies--Britain, France, and Russia. Under the command of Major General John J. Pershing, more than 2 million U.S. soldiers fought on battlefields in France.

During WWI, the Turks slaughtered approximately 1.5 million Armenians out of an initial population of about 2 million. This act of genocide would later attract the attention of Hitler and was partly responsible for sowing the seeds of the Holocaust. Despite pressure from Armenians and social justice advocates, it is still illegal in Turkey to talk about what happened to Armenians during this era.

On September 29, 1918, Bulgaria became the first of the Central Powers to sign an armistice, bringing World War I one step closer to closure. Others would soon follow, including Germany which requested a cease-fire on October 3, 1918.

Although the use of toxic chemicals as weapons dates back thousands of years, the first large scale use of chemical weapons was during World War I, leading some historians to refer to it as "the chemists' war".

Some Americans disagreed with the United States' initial refusal to enter WWI. A group of U.S. pilots formed the Lafayette Escadrille, which was part of the French air force and became one of the top fighting units on the Western Front. It was named in honor of the Marquis de Lafayette, hero of the American and French revolutions.