The new men were often not even proficient in the use of their own weapons, and once in combat, could not receive enough practical instruction from veterans before being killed or wounded, sometimes within the first few days. Under such conditions, many soldiers suffered a crippling loss of morale, while veterans were kept at the front until they were killed, wounded, or incapacitated by battle fatigue or illness. Incidents of soldiers going AWOL from combat duty as well as battle fatigue and self-inflicted injury rose rapidly during the last eight months of the war with Germany. As one historian concluded, "Had the Germans been given a free hand to devise a replacement system..., one that would do the Americans the most harm and the least good, they could not have done a better job."