This was further refined in Vietnam, the outcome being a new system, which was called the DEROS (date of expected return from overseas) system. Every individual serving in Vietnam, except general officers, knew before leaving the United States when he or she was scheduled to return. The tour lasted 12 months for basically everyone except the Marines who, known for their one-upmanship, did a 13-month tour (Lawson, 1995). .
The DEROS system was introduced to help the soldier out by minimizing mental and psychological damages caused by war. Another problem that the military officials were trying to solve was to lower the casualty rate and return more soldiers home healthy than any other previous war. .
The disadvantages to DEROS were not clear and some time elapsed before they were noticed. DEROS was a very personal thing; each individual was rotated on his own with his own specific date. This meant that tours in Vietnam were solitary, individual episodes. It was rare, after the first few years of the war, those whole units were sent to the war zone simultaneously (Goodwin 1989). .
Therefore the war became a rather solitary war, where one soldier was sent alone, and then proceeded to return back home alone. Therefore it was hard to get close to anyone, because everyone was on a different rotating schedule, and different people were coming and going everyday. Even if a soldier did get close to other soldiers, they had to go through the pain of losing them if they died. So if the soldier only worried about himself, then he would not have feelings for other soldiers. Many friendships were made during the Vietnam War and many sacrifices were made for friends, sometimes even the greatest sacrifice, death was made. However, the division between veteran soldiers and the new soldiers was often very significant, and that caused the unit to not bond the way units had in wars from the past, such as WWII, where units were very close to each other.
