(Capcom's primary storyline)
The 1st Special Forces Operational Detachment-Delta (1st SFOD-D), popularly known as Delta Force, is an elite special operations force of the United States Army, under operational control of the Joint Special Operations Command. It is tasked with specialized missions such as hostage rescue and counter-terrorism, as well as direct action and reconnaissance against high-value targets.
Delta Force was established in the 1970s when the operations of the British Special Air Service indicated an increasing trend in unconventional warfare.
Raccoon City mission
In September 1998, a feud erupted between the U.S. military and the Umbrella Corporation over the G-Virus. Dr. William Birkin, its developer, sought to hand it over to the military in exchange for asylum. Highly prized by both parties for its promise in bio-weapons development, the Umbrella Security Service's botched Operation: NESTWRECKER led to the t-Virus enveloping Raccoon City on September 24. Within a few days, the situation was already out of control, and the U.S. President, the National Security Council, and the Joint Chiefs of Staff began discussing the option of bombing the city as an effective means of containment. Although the U.S. Army was prohibited from going into Raccoon City due to the sensitive nature of the mission, only the Delta Force team was sent in on the night of September 28 to apprehend the G-Virus. As a trump card, they were entrusted with an experimental rail cannon, the Sword of Paracelsus, to use against any "G" they may encounter.
Thanks to a number of moles the U.S. government had within Umbrella USA, it was understood that Dr. Birkin's facility could be reached through the company's private subway. However, Delta Force's exploration of the subway led them to the wrong location, and they found their way to Umbrella's Incineration Disposal Plant P-12A in Raccoon's industrial zone instead. Aware of the intrusion, Umbrella's paramilitary leader for city operations Colonel Sergei Vladimir gave the order for five T-103s to be dropped at the yard to ambush and destroy the team. Though they were in possession of an experimental anti-B.O.W. weapon, Sword of Paracelsus, the railgun was left unused in the battle, and the Tyrants were defeated with explosives at the cost of the entire unit. Former soldier Jill Valentine, who was given the honor of training alongside Delta Force in bomb disposal, escaped from the city via the scrap yard and saw their bodies.
On October 1, almost everything within Raccoon City's limits was destroyed when the military bombed the city in order to contain the unstoppable deadly virus from spreading to the outside world.
Consequences of Raccoon City
Following Delta Team's loss, the U.S. military began establishing new units trained in anti-B.O.W. combat. USSTRATCOM's Anti-Umbrella Pursuit and Investigation Team was established immediately after the city's destruction, and was tasked with covert operations. The more conventional and larger Federal Bioterrorism Commission was established to tackle B.O.W.s in a more conventional manner.