20th Century
By the beginning of the 20th century, the Ottoman Empire was disintegrating. World War I and its aftermath saw its end, during which time Assyrians (and Armenians and Greeks) suffered the a genocide occurred (1914 to 1922), where an estimated two-thirds of Assyrians died in organized massacres, starvation, disease, and systematic kidnapping and rape.
Assyrians promeniently served in Iraq Levies organized by the British in 1919.
In 1932, Assyrians refused to become part of the newly-formed state of Iraq and instead demanded their recognition as a nation within a nation. The Assyrian leader Mar Eshai Shimun XXIII asked the League of Nations to recognize the right of Assyrians to govern the area known as the "Assyrian triangle" in northern Iraq. Eventually this led to the Iraqi government to commit its first of many massacres against its minority populations (see Simele massacre).
Read more about this topic: History Of The Assyrian People