"Victory is the main objective in war. If this is long delayed, weapons are blunted and morale depressed. When troops attack cities, their strength will be exhausted.
When the army engages in protracted campaigns the resources of the state will not suffice.
When your weapons are dulled and ardor dampened, your strength exhausted and treasure spent, neighboring rulers will take advantage of your distress to act. And even though you have wise counselors, none will be able to lay good plans fr the future.
Thus, while we have heard of blundering swiftness in war, we have yet seen a clever operation that was prolonged.
For there has never been a protracted war from which a country has benefited."
---Sun Tzu The Art of War/ Chapter II Waging War