Battle of Boquerón is located in Paraguay

The Battle of Boquerón was a battle fought from September 7 to 29 in 1932 between the Bolivian and Paraguayan armies in and around the stronghold of Boquerón. It was the first major battle of the Chaco War. The outpost (fortín) of Boquerón, among others, had been occupied by Bolivian troops since late July 1932 following instructions of president Daniel Salamanca leading to the escalation of the border conflict into a full-scale war.

• http://en.wikipedia.org/wiki/Battle of Boquerón