civil war
US /ˌsɪv.əl ˈwɔːr/
UK /ˌsɪv.əl ˈwɔːr/

1.
a war between citizens of the same country
:
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The country was plunged into a devastating civil war.
•
The American Civil War lasted from 1861 to 1865.
a war between citizens of the same country