Why do soldiers shave?

Answer 1

Not all soldiers shave, most armies allow beards for ethic soldiers that have beards as part of their cultures, neatly trimmed beards etc. In many cultures a bearded man was seen to be exceptionally virile, or warlike. A man without a beard was still a child or youth. However Alexander the great ordered his soldiers to be clean shaven, fearing that their beards would serve as handles for their enemies to grab and to hold the soldier as he was killed.

Answer 2

There are two reasons for this; one is practical, the other is a matter of tradition...of sorts.

The practical reason for requiring service members to shave is two-fold. The first is for hygienic reasons. Soldiers in particular find themselves in some of the most unhygienic locations. Poor hygiene leads to parasitic infestations such as fleas, lice, and crabs. These reduce the effectiveness of a fighting force. All service members being in close proximity with each other will naturally pass these infestations on in an epidemic manner, which further reduces the effectiveness of a fighting force.

The second part of this is an advent of modern warfare, the use of chemical, biological, and nuclear weapons. One of the primary defenses a soldier has against contamination from an NBC attack is the American Gas Mask (M17 and the new M40) cannot be properly sealed if the wearer has a beard or excessive facial hair. If the service member cannot seal his mask, he will become a casualty to NBC attack and is therefore a liability to his unit, thereby reducing the effectiveness of the fighting force.

The more traditional reason for requiring service members to shave daily is uniformity. In Army parlance, all service members, all soldiers are olive drab, general issue. There can be little to distinguish one from the other because all are equally important to the mission objective. If one receives special dispensation or treatment, the whole unit suffers, and the mission fails.

The mission can never fail.