Alistair Stanley was a Major in the 22nd Regiment (SAS), and was the original Rainbow Five. He, along with Domingo "Ding" Chavez and John Clark, defused a terrorist situation aboard a jet liner before Rainbow had even set up.
After the second instance of Rainbow deployment, terrorists took control of World Park in Spain, prompting Clark to deploy both Rainbow teams to the mission. Chavez' Team Two deployed from the roof of the terrorist's base, whilst Stanley's Team One attacked from below, killing off the survivors of the terrorist group.
It was then that Rainbow had it's first set-back. Provisional IRA terrorists took control of a hospital in direct proximity to Rainbow's Hereford base, with the intention of killing as many Rainbow operatives as possible. Stanley's Team were on call, and deployed to the area. PIRA insurgents armed with AKMS assault rifle opened fire on the Team, causing two fatalities, and wounding Stanley in the head. Both cells were defeated by combined support from the remainder of Rainbow.
At the end of Rainbow Six, Stanley had resumed his post after recovering in hospital.