The thirty-six stratagems, escaping is the best.
But The Art of War by Sun Tzu says, when you surround an army, leave an outlet.
The so-called 'surround an army, leave an outlet,' similar to encircling three sides and leaving one open, means that when you have the enemy surrounded, you must deliberately leave a gap, letting the enemy feel there's an opportunity to exploit, a route to escape, so the besieged enemy doesn't feel trapped without hope and fight desperately to the death.
Now the Knight Mercenary Group is not surrounding three sides and leaving one open; they're doing the opposite, leaving three sides open for Gao Guang and his team to escape immediately.
But Gao Guang didn't believe the Knight Mercenary Group didn't understand even this basic principle.