Battle of El Carmen
1934 CE.
Shown on the map at -21.641°, -62.269°.
The Battle of El Carmen was an engagement of the Chaco War between Bolivia and Paraguay which took place in November 1934. It was one of the largest battles of the war and a decisive Paraguayan victory, where a large Bolivian force was surrounded in a pincer movement and made to surrender, contributing decisively to later Paraguayan advances towards the foothills of the Andes.
Text from the Wikipedia article Battle of El Carmen, licensed CC BY-SA 4.0.