The Ottoman Empire was responsible for the Armenian Genocide, which resulted in the deaths of an estimated 1.5 million Armenians.

Unrestricted Submarine Warfare was the German policy of attacking all ships, including neutral ships, in the waters around Britain.

The Battle of the Somme was the deadliest battle of World War I, with over 1 million casualties.

Chlorine Gas was the first chemical weapon used on a large scale in warfare, and it was used by the Germans at the Second Battle of Ypres.

Germany was responsible for the sinking of the Lusitania, which resulted in the deaths of over 1,000 people, including 128 Americans.

The Treaty of Versailles was the treaty that ended World War I and it was signed on June 28, 1919.

Russia lost the most soldiers during World War I, with an estimated 1.7 million deaths.

The Battle of Flers-Courcelette was the British offensive that failed to break through the German lines at the Battle of the Somme.

Germany was responsible for the Rape of Belgium, which involved the widespread killing, rape, and destruction of property in Belgium.

The Spring Offensive was the German offensive that pushed the Allies back to the Marne River in 1918.

Great Britain was responsible for the Gallipoli Campaign, which was an attempt to capture the Dardanelles Strait from the Ottoman Empire.

U-20 was the German submarine that sank the Lusitania.

France was responsible for the Battle of Verdun, which was one of the longest and bloodiest battles of World War I.

The Battle of Amiens was the British offensive that captured the German city of Amiens in 1918.

Great Britain was responsible for the Battle of Passchendaele, which was one of the most costly battles of World War I.