Tenth Sontaran Battle Fleet
The Tenth Sontaran Battle Fleet was a Sontaran military unit commanded by General Staal. In the late 2000s, Staal formed an alliance with teenage genius Luke Rattigan against Rattigan's own Human species and saw the installation of ATMOS, which Rattigan had supposedly developed, in half the cars on Earth, which the Sontarans used as a cover for their invasion plan. At the same time, a Sontaran ship (with many smaller ships) remained in Earth orbit. A teleport pod link connected the ship and Rattigan Academy, the school that Rattigan had founded. The Fleet was destroyed by Rattigan after he sacrificed himself to end the Sontaran invasion of Earth, just before it prepared to fire upon the planet and eradicate all of Humanity. (DW: The Sontaran Stratagem / The Poison Sky)
A survior of the Battle Fleet called Commander Kaagh landed on Earth in an escape pod and meets an old enemy Sarah Jane Smith as well as Luke Smith, Maria Jackson, Clyde Langer and eventually Brigadier Alistair Lethbridge Stewart.
Other possibly non-canonical information
Group Marshall Nathan and his subordinate, who had gained entry to the TARDIS, also belonged to the Tenth Sontaran Battle Fleet. He came from a time period sometime after 2001 (DW: A Fix with Sontarans).
