(Operation Raccoon City's backstory)
The Umbrella Biohazard Countermeasure Service (abbreviated as "UBCS") was a paramilitary organization run by the Umbrella Corporation.
In September 1998, Dr. William Birkin bought over a UBCS unit to protect him during an exchange with the US military, something Umbrella headquarters was against. They suffered heavy casualties when the USS' Alpha and Delta teams infiltrated the Umbrella facility and assassinated Birkin.
Soon after, the T-virus leaked into Raccoon City, prompting the arrival of more units to counter the zombie threat.
U.B.C.S. members have their faces covered. Some wear knitted hats and cover their faces with bandanas. Others wear balaclavas with tactical goggles, and some wear bonnie hats as well.