hit their targets. This is attributable to the inherent humanity inside the soldiers who grew up in a peaceful, equitable society. This was a problem for the US military and its allies during World War II. New training was developed and hit rates improved. The changes were small, but effective. First, instead of shooting at bull's-eye type targets, the United States Army switched to silhouette targets that mimic an average human. Training also switched from 300 yard slow fire testing to rapid fire testing with different time and distance intervals from 20 to 300 yards. With these two changes, hitting targets became a reaction that was almost automatic. Some authors have discredited S.L.A. Marshall's book, stating that the book may be more of an idea of what was occurring and not a scientific study of what was happening. Other historians and journalists have outright accused Marshall of fabricating his study. Another important factor that increased fire and hit rates is the development of camaraderie in training. Soldiers are taught that their actions do not only help or harm themselves, but the whole unit. This recurring theme in recollections collected from war veterans is the idea that they were not fighting for themselves at the time but more concerned for the people to their left and right. This ideology is ancient, recorded for example by Sun Tzu in his book The Art of War: "If those who are sent to draw water begin by drinking themselves, the army is suffering from thirst." Increase in PTSD since World War II Some research has been done to say that the increase of post-traumatic stress disorder (PTSD) in the military is caused by the increase in firing rates. This brings up the classic debate of correlation vs. causation. Many believe that other factors have been influencing PTSD such as decompression time after conflicts, and the lack of moral sovereignty in engagements. World War II and Vietnam The Vietnam War compared to World War II had markedly more anti-war demonstrations which demonstrated the publics unwillingness to involve itself in Vietnam. Along with demonstrations at home, people who were sent to fight it thought there was no reason for the engagement and so did not feel a moral obligation to fight. In contrast, many U.S. soldiers in World War II felt they were stopping an evil empire from overtaking the globe. This helped the World War