During the Vietnam War most U.S. soldiers and marines operating in the field carried a U.S. military issue 'Neck Towel' for many practical reasons:

1.  For cooling and sweat absorption:
​The tropical climate of Vietnam was hot, stick and humid leading 'Grunts' to sweat profusely. These little neck towels were used to wipe away sweat and help keep the wearer a fraction cooler.

2.  Dust and debris protection:
The dusty and sandy environment of some parts of Vietnam meant that troops' faces and necks were often exposed to airborne particulates. These little towels could be used to cover the neck and lower face, protecting them from dust and debris. 

3.  Improvised First Aid:
The neck towel could also be utilized as an improvised bandage or field dressing to treat minor wounds and injuries when more formal medical supplies were unavailable.

The humble 'Neck Towel' served as one of the most useful, versatile and practical accessories that helped many individual soldiers and marines cope with the often demanding environmental and battlefield conditions faced during the Vietnam War.