Have you ever enjoyed a pillow fight? Beating an opponent with a pillow, or throwing pillows aiming at others is a popular way of mock fighting usually in children. Since a pillow is very soft as you know, there is a rare risk of injuring others in a pillow fight, in most cases.
However, it seems different in a military school.
At the United States Military Academy, a pillow battle resulted in serious trouble, recently. A total of 30 cadets were injured, because some students filled a helmet or other hard objects in a pillow case. Fortunately, all of the wounded recovered soon.
Yahoo News: Annual pillow fight turns bloody at West Point military academy
This pillow fight is an annual event in the first-grade students at the service academy in West Point, New York. The reason dangerous objects were introduced in the pillow battle, which was merely a casual game, is unclear. I guess that someone intended to enhance the power of the pillow as a joke at first, and others followed him without deep thought.
The students may include many adolescents, which often act recklessly. So, I understand their behavior. It is quite fortunate that no fatal cases occurred in this incident.
In Japan, pillow fight is also common in children. In a school excursion, most male students have fun to throw pillows at others (Makura-nage). In a Japanese traditional inn, they usually stay in a large room with tatami together. Futon (mattress and blanket) is offered instead of a bed. So, there are no obstacles or hard objects in the bedroom. It enables them to enjoy pillow fight with safety. I never joined because I had asthma.
In general, children's games have some dangerous elements. They frequently make a battle with each other. Mock wrestling is also a fun for young children. Usually, they are not so heavy or muscular to cause severe damage to the opponent. If adults make the same thing, the risk of injury would be much raised. I remember that we played dodgeball when we were 12 years old. Different from the memory of playing it at seven years old, I was so scared to the ball thrown at me. Guys could perform a vigorous shot. I realized that dodgeball was a dangerous game for teenagers.