Battle of Ingavi (1935)
1935 CE.
Shown on the map at -19.917°, -60.783°.
The Battle of Ingavi was the last battle fought in the Chaco War between Bolivia and Paraguay. The Bolivian 6th Division attacked Fort Ingavi, an outpost far away from the rest of the frontline garrisoned by a small force, but its defenders managed to delay it enough for reinforcements to arrive. The reinforced Paraguayans then partly surrounded the attackers and made them surrender.
Text from the Wikipedia article Battle of Ingavi (1935), licensed CC BY-SA 4.0.