Fog of war

For the documentary film, see The Fog of War.

The fog of war is the lack of knowledge that occurs during a war. It includes military commanders' incomplete intelligence regarding their enemy's numbers, disposition, capabilities, and intent, regarding features of the battlefield, and also including incomplete knowledge of the state of their own forces. Fog of war is caused by limited reconnaissance, by the enemy's feints and disinformation, by delays in receiving intelligence and difficulties passing orders, and by the difficult task of forming a cogent picture from a very large (or very small) amount of diverse data. When a force engages in battle and the urgency for good intelligence increases, so does the fog of war and chaos of the battlefield, while military units become preoccupied with fighting or are lost (either destroyed by enemy fire or literally lose their way), reconnaissance and liaison elements become unavailable, and sometimes while real fog and smoke obscure vision.

The term is ascribed to the Prussian military analyst Carl von Clausewitz, who wrote: "The great uncertainty of all data in war is a peculiar difficulty, because all action must, to a certain extent, be planned in a mere twilight, which in addition not infrequently — like the effect of a fog or moonshine — gives to things exaggerated dimensions and unnatural appearance."

Experienced soldiers often liken it to following a technical conversation when drunk.

Some people think the term originates from the fog-like smoke that would be created by the use of gunpowder during a battle. During such battles commanders would often find it difficult to observe their enemies, their allies and even their own forces. In some cases the fog occasionally meant that regiments or battalions or companies would charge at each other only to miss and become lost in the smoke. Also some commanders would deliberately recreate this fog by the use of gunpowder-based weapons and/or the burning of the landscape as to hide the activities of their forces.

Much of the modern military's technological efforts, under the rubric of command and control, seeks to reduce the fog of war, although even the most advanced technology does not eliminate it.

Abstract and military board games sometimes try to capture the effect of the fog of war by hiding the identity of playing pieces by keeping them face down, or turned away from the opposing player (as in Stratego). In some games, such as the Kriegspiel chess variant, playing pieces are hidden altogether by tracking their locations on paper or on a hidden board. Complex double-blind miniatures wargames may make use of two identical game boards or cloth models, and one or more referee players.

In military and adventure video and computer games, the term "fog of war" is jargon referring to enemy units or characters being hidden from the player.