SG-2 was one of the original nine SG teams created by presidential order after Colonel Jack O'Neill's second expedition through the Stargate to Abydos. Originally it was a three-man team led by Major Charles Kawalsky, with Carl Warren and Casey. (SG1: "Children of the Gods")
Kawalsky led the team on one mission before his death, after which Major Louis Ferretti assumed command. Some weeks prior to Senator Robert Kinsey shutting down the Stargate program, SG-2 made contact with the citizens of Argos to establish how the people were adjusting to their newfound normal lifespans after SG-1's mission there (SG1: "Brief Candle", "Politics").
Feretti was scheduled to recover SG-1 after they traveled without authorization to the presumed staging ground of Apophis' attack on Earth, but the Stargate would not engage. (SG1: "The Enemy Within", "Within the Serpent's Grasp")
By 2000, SG-2 was led by Major Michael Patrick Coburn, who repeatedly found his team tasked with securing the Stargate on worlds to which SG-1 had been dispatched, including Kheb and P3X-888. (SG1: "Maternal Instinct", "The First Ones")
By the latter mission, his team included Captain Michael Griff and Captain Ben Pierce; Griff would soon be promoted to Major and placed in command of SG-2; he led the team in search of SG-1 when the latter unit went missing on P3R-118, and in providing security for the scientific outpost on M4C-862. (SG1: "Prodigy")
In 2001, after discovery of the android Reese, SG-2 was sent by Major General George S. Hammond to make contact with the Asgard through the Hall of Wisdom on K'Tau, but was unsuccessful. (SG1: "Menace")
In 2002, the team gathered artifacts from the planet P36-230 together with Jonas Quinn; their return through the Stargate hindered the Tok'ra's ability to successfully dial Earth while attempting to evacuate their besieged base. (SG1: "Allegiance")
In 2004, they discovered a column on P3X-439 that had inscriptions indicating that there is an Ancient library database inside that structure. SG-1 extracted that knowledge before the planet was attacked by Anubis's fleet. (SG1: "Lost City, Part 1")