The occupation of Western Armenia by the Russian Empire during World War I began in 1915 formally ended by the Treaty of Brest-Litovsk. It was sometimes referred to as the Republic of Van by Armenians, because the occupation imitated in Van. Aram Manukian of Armenian Revolutionary Federation was the de facto head until July 1915. It was briefly referred to as "Free Vaspurakan". After a setback beginning in August 1915, it was re-established in June 1916. From December 1917, it was under Transcaucasian Commissariat, with Hakob Zavriev as the Commissar, and during the early stages of the establishment of First Republic of Armenia, it was included with other Armenian National Councils in a briefly unified Armenia.

This provisional government relied on Armenian volunteer units, forming an administrative structure after the Siege of Van around April 1915. Dominant representation was from the Armenian Revolutionary Federation. Aram Manukian, or "Aram of Van," was the administration's most famous governor.

During the Siege of Van, there were between 67,792 (according to the 1914 Ottoman population estimates) and 185,000 Armenians (according to the Armenian Patriarch's 1912 estimate) in the Van Vilayet. In the city of Van itself there were around 30,000 Armenians, but more Armenians from surrounding villages joined them during the Ottoman offensive.

The conflict began on April 20, 1915, with Aram Manukian as the leader of the resistance; it lasted for two months. In May, the Armenian battalions and Russian regulars entered the city and drove the Ottoman army out of Van.

...
Wikipedia