the.com/fog of war

means The confusion and uncertainty commanders and participants face during a conflict, where incomplete or wrong information makes clear decision-making nearly impossible.

from The phrase traces to the 19th-century Prussian military theorist Carl von Clausewitz, who wrote in 'On War' about how uncertainty — a 'fog' obscuring the true picture — clouds every action in battle. He didn't coin the exact phrase 'fog of war' in those words, but his repeated imagery of fog, friction, and uncertainty is where the idea was born; the tidy English phrase crystallized later from that groundwork and stuck because it captures something real: no battle plan survives contact with an enemy who doesn't share your map.