16-character formula, esp. Mao Zedong's mantra on guerrilla warfare: 敵進我退 ，敵駐我擾 ，敵疲我打 ，敌进我退 ，敌驻我扰 ，敌疲我打 ，敌退我追 when the enemy advances we retreat; when the enemy makes camp we harass; when the enemy is exhausted we fight; and when the enemy retreats we pursue