Which book by Carl Von Clausewitz is the fog of war from?

The phrase "fog of war" is not from a specific book by Carl von Clausewitz. While he did not use the exact phrase, it's a concept derived from his work, particularly from his seminal book "On War".

In "On War," Clausewitz emphasizes the uncertainties, complexities, and limitations of warfare, highlighting the difficulty of understanding and controlling the battlefield. He describes the challenges of gathering accurate information, the limitations of human perception and judgment, and the dynamic and unpredictable nature of war. These aspects contribute to the "fog of war" where clear understanding and control are often elusive.

While not directly quoted, the phrase "fog of war" encapsulates the core of Clausewitz's observations on the unpredictability and complexity of armed conflict.