Bring war material with you from home, but forage on the enemy... use the conquered foe to augment one's own strength.
Sun TzuTo capture the enemy's entire army is better than to destroy it; to take intact a regiment, a company, or a squad is better than to destroy them. For to win one hundred victories in one hundred battles is not the supreme of excellence. To subdue the enemy without fighting is the supreme excellence.
Sun Tzu