FORT CARSON, Colo. — Some 8,000 soldiers with the 4th Infantry Division were purposely tear-gassed days after returning from holiday leave as part of a massive demoralizing event in which soldiers scaled obstacles, ran up hills, and counted down the days until their time was up in the U.S. Army.

"The purpose of this event was to destroy unit cohesion. Leaders at echelon participated in this event with Soldiers," said Dee McNutt, an Army spokesperson. "The massive use of CS [gas] was intended to interfere with the formations and to deter participants from leaving the course."

Division leadership overseeing the event at Fort Carson, Colorado, marked the course with tear gas so that soldiers participating in the event would vomit, cry, and be motivated to finish. Officials had planned to fire live AK-47 rounds toward the soldiers and drop high-explosive artillery rounds nearby, but safety concerns over potential gunshot and shrapnel wounds led the Army to only choke and blind soldiers with toxic gas.

According to officials, troops are usually informed ahead of time about whether they may be exposed to tear gas as a safety precaution. But officials say they wanted to “train like we fight” and eliminate any last semblance of motivation for soldiers after they returned from the holidays.