Complex sentence: The original plan was that the first column, commanded by Wenceslao Robles, would seize Corrientes while a second column of 12,000 men, commanded by Antonio de la Cruz Estigarribia, would then advance to the east of Corrientes and capture Brazilian possessions on the Uruguay river.
Split into simpler sentences: The original plan was that the first column, commanded by Wenceslao Robles, would seize Corrientes. A second column of 12,000 men commanded by Antonio de la Cruz Estigarribia would then advance to the east of Corrientes and capture Brazilian possessions on the Uruguay river.