SG-11 was created in 1998 along with SG-10 and SG-12. (SG1: "In the Line of Duty")
Their first mission was to help relocate the Nasyans. (SG1: "In the Line of Duty")
Initially SG-11 was the engineering corps led by Captain Laurence Conner, promoted after leaving SG-9. The entire team was captured and later executed by Apophis. (SG1: "Spirits", "Rules of Engagement")
The new group was an archaeological unit led by Major Gil Hawkins, Loder, Sanchez and Dr. Robert Rothman. This team was sent to what they didn't know was the original Goa'uld homeworld and were killed in action, Loder and Sanchez when they were both attacked by an Unas while Hawkins and Rothman were later killed by Teal'c and Jonathan J. O'Neill after it was revealed that Hawkins and Rothman were possessed by the same Goa'uld symbiote . (SG1: "The First Ones")
During the invasion of Langara by Anubis, Jack O'Neill requested SG-11 along with SG-15 to act as "technical advisers." (SG1: "Homecoming")
After that, the team designation went to be an engineering unit again, under Colonel Martin Edwards, with Major Evan Lorne, Lt. Menard, Lt. Ritter and Lt. Woeste, SG-11 led an extended mining survey. (SG1: "Enemy Mine")
They were also sent, together with SG-21 and parts of SG-1 to track down the Kull warrior that wiped out Earth's Alpha Site. (SG1: "Death Knell")