The Terra Quadrant lies in the Sol Sector and consists of the Alpha Centauri, Arcturus, Asylum, Camelot, Celeste, Forcke, Mastif, Mauer, Murphy, Proxima Centauri, Ross 248, Sirius, Sol, Timonen, Wattenbarger and Weslyn systems.
The Terra Quadrant hosts the Sol System, which is the location of the human homeworld of Earth. Therefore, it is the capital quadrant of the Terran Confederation and possibly one of the most densely populated. It is also home to the Confederation Headquarters, the command center for the entire Confederation Space Navy, and is therefore a major center of military activity.
The Terra Quadrant is one of the most heavily-defended quadrants due to its strategic importance. It was briefly invaded during the Terran-Kilrathi War in 2668 when the Kilrathi Empire launched a massive assault that saw the eradication of Sirius and the near-destruction of Earth. The Confederation Space Navy, with assistance from the Free Republic of the Landreich, was successful in fending off the attack, but Confed was left on the brink of defeat as a result of the massive losses sustained.
Confed won the War with the destruction of Kilrah in 2669, restoring security in the Terra Quadrant. However, the region was threatened again by the resurgence of the Nephilim from 2681 onward, forcing humanity on the defensive.