This is related to the term, "the fog of war". Basically it means that when you are fighting for your life, things are very confusing. Between adrenaline, noise, smoke, and the need to make rapid life-and-death decisions, time gets distorted along with the minds of the participants.

There is a saying that no plan of action survives contact with the enemy. The heat of battle is partially to blame for this. Snap judgements get made, orders are forgotten, and men and material get misdirected.