Battle of Ituzaingó
1827 CE.
Shown on the map at -30.245°, -54.875°.
The Battle of Ituzaingó, also known as the Battle of Passo do Rosário, was a pitched battle fought in the vicinity of the Santa Maria River, in a valley of small hills where a stream divided the valley into two. After a two-year series of continuous sundry skirmishes in the Banda Oriental (present-day Uruguay and Rio Grande do Sul) and along the border of this region with Brazil, the advancing Argentine Army (including Orientals) engaged in combat with the Imperial Brazilian Army. The battle lasted for about six hours, beginning at around six in the morning of 20 February 1827.
Text from the Wikipedia article Battle of Ituzaingó, licensed CC BY-SA 4.0.