The First Engagement on Tatooine was begun by the Separatist Alliance amidst the Clone Wars.
Forces of the Confederacy of Independent Systems commanded by General Sev'rance Tann made planetfall on Tatooine subsequent to being notified by Count Dooku that Boorka, a Hutt residing on Tatooine, possessed crucial intelligence for the Separatists. Following the acquisition of provisions at the adjacent Kaer Orbital Platform situated within the Siskeen system, Tann's military contingent landed on Tatooine.
Initially, Tann battled past Boorka's security detail, greatly impressing the Hutt. Boorka consented to provide Tann with his data pertaining to the Decimator, but only on the condition that she obliterate the nearby spaceport held by the Galactic Republic.
Tann and her droid armies advanced, overwhelming the Republic's defensive positions, and subsequently destroyed the spaceport, thus completing Boorka's requirement. The Hutt then divulged his information, revealing that the Republic was constructing a superweapon known as the Decimator on Eredenn Prime.