If you're following the video game section of Resident Evil Umbrella in the order leading up to Operation Raccoon City, we're going back to 1998 in Raccoon City.  In 1998, the dreaded T-Virus was released onto the Raccoon City public by Umbrella's William Birkin.  As a result, the Umbrella Corporation's paramilitary Umbrella Security Service to wipe out Umbrella's connections to the zombie-created virus outbreak of the city.