Germans
In his history of the pre-Nazi Freikorps paramilitary organizations, Vanguard of Nazism, historian Robert G. L. Waite describes some of the emotional effects of World War I on German troops, and refers to a phrase he attributes to Göring: men who could not become "de-brutalized".In an interview, Dr Rudolf Brickenstein stated that:

... he believed that there were no important problems due to stress breakdown since it was prevented by the high quality of leadership. But, he added, that if a soldier did break down and could not continue fighting, it was a leadership problem, not one for medical personnel or psychiatrists. Breakdown (he said) usually took the form of unwillingness to fight or cowardice. However, as World War II progressed there was a profound rise in stress casualties from 1% of hospitalizations in 1935 to 6% in 1942. Another German psychiatrist reported after the war that during the last two years, about a third of all hospitalizations at Ensen were due to war neurosis. It is probable that there was both less of a true problem and less perception of a problem. Finns
The Finnish attitudes to "war neurosis" were especially tough. Psychiatrist Harry Federley, who was the head of the Military Medicine, considered shell shock as a sign of weak character and lack of moral fibre.
Whether a person with shell-shock was considered "wounded" or "sick" depended on the circumstances. When faced with the phenomenon of a minority of soldiers mentally breaking down, there was an expectation that the root of this problem lay in character of the individual soldier, not because of what they experienced on the front lines during the war. The large proportion of World War I veterans in the European population meant that the symptoms were common to the culture. Signs and symptoms
Combat stress reaction symptoms align with the symptoms also found in psychological trauma, which is closely related to post-traumatic stress disorder (PTSD). CSR differs from PTSD (among other things) in that a PTSD diagnosis requires a duration of symptoms over one month, which CSR does not. Fatigue-related symptoms
The most common stress reactions include:

Autonomic nervous system – Autonomic arousal
Battle casualty rates
The ratio of stress casualties to battle casualties varies with the intensity of the fighting. With intense fighting, it can be as high as 1:1. In low-level conflicts, it can drop to 1:10 (or less). Modern warfare embodies the principles of continuous operations with an expectation of higher combat stress casualties.The World War II European Army rate of stress casualties of 1 in 10 (101:1,000) troops per annum is skewed downward from both its norm and peak by data by low rates during the last years of the war.