What is Shel shock?

Shell shock(Combat Stress Reaction (CSR)) is a military term used to categorize a range of behaviours resulting from the stress of battle which decrease the combatant's fighting efficiency. The most common symptoms are fatigue, slower reaction times, indecision, disconnection from one's surroundings, and inability to prioritize. Combat stress reaction is generally short-term and should not be confused with PTSD which is a long-term disorder attributable to combat stress.