The attack on the SGC came from three sides at once.
The first attack came over a year prior to the others, when a trojan horse was introduced into the computer systems, quietly infecting most of the critical systems on base, including iris control and the dialing computers. Introduced on an airman’s personal flash drive, the virus propagated throughout the facility within six months and sat dormant until it noted a phone call from a particular number at a certain time. Within moments, a mercenary strike team had control over critical functions of the SGC.
The triggering event for the call was the return of SG12, commanded by Capt. Steven Browder. As the last member of the team stepped through the gate on the far end, the call came in and the dialing computers crashed, keeping the SGC personnel from closing the iris or forcing a shutdown of the gate. Behind them came the second prong of the attack--a mercenary force lying in wait and undetected by 12 near the gate. An assault team rushed the gate and took out Browder and two others on his team before the gate defense forces repelled them.
Over the next thirty minutes, before the gate auto-closed, the attacking force was able to neutralize the gateroom defenders and establish a foothold in the SGC.
Meanwhile, the third prong of the attack began on the surface, infiltrating the SGC through emergency exits and locking relief forces out of the mountain through their control of the mountain’s computer systems. Made up of rogue elements of the NID and a handful of former SGC members subverted by enemies of the program, the attacking force began to take the base, level by level, from the top down, reaching as far as level 9 relatively uncontested.
This was the extent of the attacks’ unmitigated successes.
Many of the teams were onworld, being variously between assignments or in training rotations. Members of SG6 and SG8 were working on deciphering and testing an ancient communication device with the cooperation of the Prometheus and a team from Area 51 on board at the time of the attacks. Unconnected from the computer systems--and incapable of being infected by the virus--they were able to get word to them and other offworld teams about the situation in the SGC. The Prometheus was quickly able to gather in two other Earth ships and attack the foothold site from orbit, disrupting resupply and reinforcement operations from there.
Meanwhile, SG5 had all been off-base at the time of the attack. With the help of friends at Area 51, they were able to convince Pentagon brass of the seriousness of the situation, and within hours, Cochraine and SG5 were guiding hastily-briefed special forces teams into the mountain to retake it. Though the invaders were prepared for a counterattack from outside, the skill of the special forces teams put them at an advantage.
Within the mountain, Benson, Levitz, and Fulci coordinated the internal defense and counterattack, gathering SG4, SG7, and the remnants of SG6, SG8, and SG9 to the cause, along with whatever other combat personnel remained on base. Despite the lack of working blast doors, they were able to contain the incursion to the gateroom level and stop the surface forces from easily penetrating below level 10. Fighting, however, found its way to every floor and most every corridor. Fire broke out in the main dining facility, and several offices and labs were heavily damaged in the fighting.
Mimi Montalvo worked tirelessly to rescue and treat the wounded, commanding a hodge-podge team of combat medics from the various teams and the infirmary. When Dr. Frazier’s deputy was wounded, Montalvo took over to help run the infirmary itself, performing two emergency surgeries on her own.
The attempted incursion ended just over 24 hours after it began. Forty-seven men and women of the SGC had been killed, and nearly all the rest of them wounded in some form or another, including General Hammond. Several of the wounded would ultimately retire or take medical discharge as a result of their wounds. All remaining offworld teams were recalled and the work of rebuilding and reorganizing began.
Within a month, General Hammond had transferred to Washington, promoted to the Pentagon and given command of the new overarching structure to which the SGC, the offworld bases, and the space fleet all belonged. Promoted in his wake was Jack O’Neil, now a Brigadier General, and given command of the SGC and its offworld teams. O’Neil shook up many of the team assignments and ordered a top-to-bottom check up of the entire SGC to ensure greater security and make sure all the damage had been repaired.
Most people who participated in the defense and retaking of the SGC were decorated for bravery or heroism in some fashion or another. Judith Benson was promoted to full Colonel, and Matt Levitz is “colonel-selected” awaiting promotion. Malachi Cochraine and Keiko Serra were both promoted to Captain and put in charge of SG5 and SG8, respectively. Mimi Montalvo was promoted to Major and made Dr. Frazier’s permanent deputy in the infirmary. Tony Fulci was promoted to Lieutenant Colonel and made second-in-command of the facility’s security team.
O’Neil tried to maintain the environment and command atmosphere of his predecessor, the beloved Gen. Hammond, but the incursion necessitated certain changes, and the immediate focus of the SGC’s mission became the incursion itself. Anyone among the soldiers who attacked who might have known something about why, or what they were after, appeared to have died. With the Jaffa uprising putting pressure on the System Lords and keeping them mostly at bay, the identity of those responsible for the attack remains in doubt.