One defends when his strength is inadequate, he attacks when it is abundant.
A warrior who is prepared to fight must also be prepared to die.
One mark of a great soldier is that he fight on his own terms or fights not at all.
Of old the expert in battle would first make himself invincible and then wait for his enemy to expose his vulnerability.
All warfare is based on deception. If your enemy is superior, evade him. If angry, irritate him. If equally matched, fight and if not: split and re-evaluate.
When strong, avoid them. If of high morale, depress them. Seem humble to fill them with conceit. If at ease, exhaust them. If united, separate them. Attack their weaknesses. Emerge to their surprise.