The 1918–1920 Armenian-Azerbaijani war established contested borders and ethnic demographics in the South Caucasus that underpin conflicts in the region to this day.
Key Facts
- Duration
- 1918–1920
- Region
- South Caucasus (modern Armenia and Azerbaijan)
- Key disputed territory
- Karabakh region
- Notable atrocities
- March Days, September Days, Shusha massacre
- Ended by
- Soviet 11th Army invasion and occupation
Location
Cause → Event → Consequence
The collapse of Russian imperial authority during World War I and the Russian Civil War created a power vacuum in the South Caucasus. The newly formed Azerbaijan Democratic Republic and Republic of Armenia each advanced rival territorial claims over regions with mixed populations, including Karabakh and parts of the Erivan Governorate, fueling armed confrontation between competing militias backed by each state.
Between 1918 and 1920, Armenia and Azerbaijan fought a series of territorial conflicts across the South Caucasus. Both governments supported ethnic militias in disputed zones, resulting in widespread massacres and ethnic cleansing on both sides. Key episodes of mass violence included the March Days, the September Days, and the Shusha massacre, which dramatically altered the demographic composition of the contested regions.
The war ended when the Soviet Red Army's 11th Army invaded and absorbed both Azerbaijan and Armenia into Soviet rule, temporarily freezing the territorial disputes. The ethnic cleansing and demographic shifts produced during the conflict left unresolved grievances that would resurface following the dissolution of the Soviet Union in the form of the Nagorno-Karabakh conflict.
Belligerents & Mobilization Analysis
Side A
1 belligerent
Side B
2 belligerents