At the prestigious military academy West Point, pillow fights have been a tradition since at least 1897. Apparently, generations of students at the publicly funded academy, where many of the Army’s top leaders are trained, have ended their summer training with a huge nighttime pillow fight, or “spirit exercise”.

This year, the pillow fight turned violent and left 30 cadets injured, including 24 with concussions, according to West Point. Blood was spilled as some cadets swung pillowcases packed with helmets that split lips, broke at least one bone, dislocated shoulders and knocked some unconscious.

“West Point applauds the cadets’ desire to build esprit and regrets the injuries to our cadets,” academy spokesman Lt. Col. Christopher Kasker told The New York Times. “We are conducting appropriate investigations into the causes of the injuries.”

Freshmen at West Point are called plebes. At least one plebe was loaded into an ambulance post-pillow fight.

“My plebe was knocked unconscious and immediately began fighting when he came to,” an upperclassman wrote on Yik Yak. “I was so proud I could cry.”