[micheljansen]

Yep, from Sun Tzu's Art of War:

"When you surround an army, leave an outlet free. Do not press a desperate foe too hard."

-- http://classics.mit.edu/Tzu/artwar.html

I think this is also the first time I've heard it quoted in an appropriate context, as opposed to business blabla.

[nodata]

To quote coolsubmission on reddit:

This does not mean that the enemy is to be allowed to escape. The object, as Tu Mu puts it, is "to make him believe that there is a road to safety, and thus prevent his fighting with the courage of despair." Tu Mu adds pleasantly: "After that, you may crush him."

[hga]

Also comes up in discussing the types of ground. "Death" or "desperate" ground is where you fight at all costs, since otherwise the cost is death.

[mrev19]

unless you get saved by eagles

[alexeisadeski3]

You must not follow the Syrian Civil War very closely!