In Chapter 23, Greene examines unconventional or “dirty” warfare as a strategic approach to situations in which conventional rules, ethics, and patterns do not provide an advantage. According to Greene, surprise and misperception are the key instruments of unconventional warfare because an adversary needs a clear understanding of reality to function effectively. Without this clear perception, the entire strategic process breaks down.

Greene refers to a wide range of historical, literary, and military examples to show how misperception can be engineered on a large scale. During the Allied deception campaign in preparation for the invasion of Normandy, the British intelligence services used Adolf Hitler’s perceptions to their advantage by combining facts and false assertions in such a way as to create a “false mirror” of what he already expected to see. The false army formations, such as the fictional FUSAG (First United States Army Group), used misinformation and false intelligence to ensure that the German armies remained dispersed even after the invasion began. 

Greene extends this line of argument to earlier strategic illusions, such as Themistocles’ deception of Xerxes before the Battle of Salamis, where a manipulated defection message led to a catastrophic reaction by the Persians. Similarly, biblical and classical ambush narratives that employ feigned weakness to deceive the enemy also fall into this category.