A strategy that has been used in many wars is blockade: surround your enemy so that they can receive no provisions or support.
Without provisions, they begin to starve. Then they surrender without violence.
This strategy was used by King George in the American Revolution, General Scott in the U.S. Civil War, and President Kennedy in the Cuban Missile Crisis.
DECISION: What are the pros and cons of this strategy? If you were Caesar, would you employ it?