Second: Group Absolution

Soldiers don't just fight as individuals but also as units.
A tremendous volume of research indicates that the primary factor that motivates a soldier to do the things that no sane man wants to do in combat (that is, killing and dying) is not the force of self preservation but a powerful sense of accountability to his comrades on the battlefield.
Of course this bond has to be created and nurtured. The training and the common 'adventures' and trials should guarantee this. It needs time. Of course this bond can be surpassed by failures, losses, defeat.
The defeat of even the most elite group is usually achieved when so many casualties have been inflicted (usually somewhere around the 50 percent point) that the group slips into a form of mass depression and apathy. Dinter points out that " The integration of the individual in the group is so strong sometimes that the group's destruction, e.g. by force or captivity, may lead to depression and subsequent suicide." Among the Japanese in World War II this manifested itself in mass suicide. In most historical groups it results in the group suicide of surrender.
''Marshall noted that a single soldier falling back from a broken
and retreating unit will be of little value if pressed into service in
another unit. But if a pair of soldiers or the remnants of a squad
or platoon are put to use, they can generally be counted upon to
fight well.''
[...] If the individual is bonded with his comrades, and //"he is with "his" group, then the probability that the individual will participate in killing is significantly increased. But if those factors are absent, the probability that the individual will be an active participant in combat is quite low.
''Du Picq sums this matter up when he says, "Four brave men
who do not know each other will not dare to attack a lion. Four
less brave, but knowing each other well, sure of their reliability
and consequently of mutual aid, will attack resolutely. There,"
says du Picq, "is the science of the organization of armies in