Fujibayashi Yasutake

"It is possible to kill the enemy general with shinobi-no-jutsu and if this is done the benefit will be immeasurable. There is a secret in shinobi-no-jutsu on the skills required to kill the enemy's commander. In a case where your ninja can kill the enemy general, then it will bring an enormous benefit, as the enemy will submit without fighting."

Fujibayashi Yasutake, 1676. Bansenshukai