This is coolbert:
Here thanks to the wiki are some quotations attributed to the Duke of Wellington, Arthur Wellesley, and sourced [the attribution is confirmed] - - the Duke understanding full well the "fog of war" from his own experience and observations:
"All the business of war, and indeed all the business of life, is to endeavour to find out what you don't know by what you do; that's what I called 'guessing what was at the other side of the hill.'"
"Just to show you how little reliance can be placed even on what are supposed the best accounts of a battle, I mention that there are some circumstances mentioned in General —'s account which did not occur as he relates them. It is impossible to say when each important occurrence took place, or in what order."
"The history of a battle, is not unlike the history of a ball. Some individuals may recollect all the little events of which the great result is the battle won or lost, but no individual can recollect the order in which, or the exact moment at which, they occurred, which makes all the difference as to their value or importance. . . . "
The fog of war is a term used to describe the uncertainty in situation awareness experienced by participants in military operations. The term seeks to capture the uncertainty regarding own capability, adversary capability, and adversary intent during an engagement, operation, or campaign."
"(War is an area of uncertainty; three quarters of the things on which all action in War is based on are lying in a fog of uncertainty to a greater or lesser extent. The first thing (needed) here is a fine, piercing mind, to feel the truth with the measure of its judgment)." - - Carl von Clausewitz.
"(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 moonlight — gives to things exaggerated dimensions and unnatural appearance.)" - - Carl von Clausewitz.
* Arthur Wellesley and US Grant were the two most outstanding senior combat commanders of the Nineteenth Century? What about Napoleon and Robert E. Lee you ask?
* The senior combat commander during the Napoleonic had a much easier time determining what was occurring on the battlefield than does the modern contemporary military man? That commander from the Black Powder Age of warfare often occupying dominant terrain was able to see the entire battle ground as combat progressed and able to the determine with accuracy the disposition of his units and the enemy BOTH often with a single glance? YET, uncertainties still existing and of such Wellington was manifestly aware!!
* Wellington and Clausewitz were contemporaries but probably never met in person. Clausewitz NEVER did use those exact words "fog of war", his magnum opus never finished a rough draft not published during his lifetime, the man tragically perishing in a cholera epidemic.
That fog of war obscuring and making difficult the decision making process of the commander on the ground. The most extreme example from modern times being that of Jellicoe at Jutland? Thirty seconds under conditions of fog, smoke, approaching darkness, uncertainty as to the exact positions of your own ships and that of the enemies - - the critical decision to further pursue or break off contact vital to the war effort, the conservation approach taken as a result both literally and figuratively of the fog of war!!