Sometimes called the first genocide of the twentieth century, the Armenian genocide refers to the physical annihilation of Armenian Christian people living in the Ottoman Empire from spring 1915 through autumn 1916. There were approximately 1.5 million Armenians living in the multiethnic Ottoman Empire in 1915. At least 664,000 and possibly as many as 1.2 million died during the genocide, either in massacres and individual killings, or from systematic ill treatment, exposure, and starvation.

The origin of the term genocide and its codification in international law have their roots in the mass murder of Armenians in 1915–16. Lawyer Raphael Lemkin, the coiner of the word and later its champion at the United Nations, repeatedly stated that early exposure to newspaper stories about Ottoman crimes against Armenians was key to his beliefs about the need for legal protection of groups (a core element in the UN Genocide Convention of 1948).

Ottoman authorities, supported by auxiliary troops and at times by civilians, perpetrated most of the persecution and mass killing. The Ottoman government, controlled by the Committee of Union and Progress (CUP; also called the Young Turks), aimed to solidify Muslim Turkish dominance in the regions of central and eastern Anatolia by eliminating the sizeable Armenian presence there.

Mass atrocities and genocide are often perpetrated within the context of war. The destruction of the Armenians was closely linked to the events of World War I. Fearing that invading enemy troops would induce Armenians to join them, in spring 1915 the Ottoman government began the deportation of the Armenian population from its northeastern border regions. In the months that followed, the Ottomans expanded deportations from almost all provinces regardless of distance from combat zones.