Sontarans were a race of warlike homunculi, who had occasional contact with War-time powers.
The majority of the Sontarans' history was dedicated to an endless war against the Rutan Host. (PROSE: The Quantum Archangel) It lasted thousands, or even millions of years, before the Doctor successfully negotiated a peace. (PROSE: The Infinity Doctors)
During the War, Sontarans (specifically the Seventy-Ninth Sontaran Assault Corps, led by Kine) were used as shock troops by House Tracolix and House Lolita in an attack on the Eleven-Day Empire. They were quickly repelled, but succeeded in their goal: stealing Faction Paradox's biodata archives and leaving behind a fusion bomb. When Lolita imposed martial law on the Empire, she enforced it using the same Sontarans. (AUDIO: The Eleven Day Empire, The Shadow Play)