Waging War

Those adept in waging war rely on provisions from the enemy.

Victory is the main object in war.

If this is long delayed, weapons are blunted and the 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 the ardour damped,

Your strength and treasure spent,

Neighbouring rulers will take advantage of your distress to act

Costs 

Resource allocation

Financial considerations

Emphasises of speed

And leveraging off your competitors