The Battle of Baltizaar involved an assault by the Bando Gora, a group of criminals who worshiped the Force, against the planet of Baltizaar.
The planet almost succumbed to the cult's fierce attack. To combat the assault, the Galactic Republic requested intervention from the Jedi Order, resulting in the dispatch of a Jedi task force to the planet. Although the Jedi force suffered losses, they ultimately drove the Bando Gora away from Baltizaar.
During the conflict, the Bando Gora captured Komari Vosa along with two other Jedi warriors. These Jedi were taken as prisoners and held within the Bando Gora's stronghold located on Kohlma. Vosa and the other Jedi endured brutal torture, which eventually led to Vosa's fall to the dark side of the Force. After her escape from prison and the killing of two fellow prisoners, she assumed leadership of the Bando Gora.
The eventual dark-side leadership of Vosa, in conjunction with Qui-Gon Jinn's maverick reputation as a Jedi which would culminate in his death at the hands of a Sith Lord, would ultimately serve as the final catalyst that drove Count Dooku to leave the Jedi Order.
Originally, Jedi vs. Sith: The Essential Guide to the Force placed the Battle of Baltizaar in 39 BBY. However, the novel Darth Plagueis more recently dates the battle to 33 BBY, which is shortly before Darth Maul's assignment to Dorvalla.