Answer:
to maintain control of key river
Explanation:
The Confederate goal in the western theater during the Civil War was "to maintain control of key river."
This is because while the Union Armies were advancing into the western theater to destroy the agricultural land of the south and at the same time disrupts the Confederate overall war strategy, the Confederate, in turn, tried to ensure that they maintain control of the major rivers of the region including the Mississippi, Tennessee, and the Cumberland to block the invasion of the Union Armies in the western theatre.