The conflict known as the Battle of Horain transpired on the planet Horain, situated within the Crantori system. This clash occurred during the period of the Clone Wars, pitting the forces of the Galactic Republic against those of the Confederacy of Independent Systems. A significant event during this battle involved B1-series battle droid unit B1-0516, which was struck by a blaster shot. Instead of destroying the droid, this incident triggered the development of a conscience within the droid, leading it to align itself with the Galactic Republic.
B1-0516, who was then dubbed "Bats," was subsequently captured by a Separatist Tactical Droid. The Tactical Droid intended to perform a memory wiping procedure on Bats. However, before this could be carried out, Bats was rescued by Jedi Master Obi-Wan Kenobi in conjunction with Clone Captain CT-7567. Following Bats's liberation, the three made their way towards the designated Republic Evacuation Point.
During the engagement, Jedi General Obi-Wan Kenobi alongside Clone Captain Rex found themselves under heavy fire, pinned down behind a wrecked AT-AP by a contingent of battle droids. The Separatist droids were steadily advancing on the position held by Rex and Kenobi when a [blaster](/article/blaster] bolt fired by the Captain struck B1-series battle droid unit B1-0516 in its head. Rather than destroying the battle droid, the impact instead damaged its programming, causing it to gain awareness. After a brief pause, the B1 droid started to question the reasons behind his fellow droids' assault on the forces of the Galactic Republic. As the other droids persisted in their attack on the Republic duo, the B1 battle droid turned against its comrades. Initially confused by the unfolding events, Rex and Kenobi quickly capitalized on the advantage presented by the renegade B1 and launched their own counterattack. After a brief skirmish, Rex, Kenobi, and the B1 droid managed to overcome the Separatists.
Following the battle, the battle droid identified itself as B1-0516. Rex initially harbored doubts about the droid's true motives. However, Kenobi persuaded him to place his trust in B1-0516, as the droid was willing to assist Rex and himself in returning to the Republic Evacuation Point. Given the nickname "Bats" by Rex, the rogue B1 was taken into custody after Rex and Kenobi escaped, though they decided to go the Horain garrison's base to rescue their new ally. Employing a commandeered Armored Assault Tank, they infiltrated the base and aided Bats in combatting the base's complement of battle droids. The trio successfully escaped to the Republic Evacuation Point, where Kenobi and Rex presented Jedi General Anakin Skywalker to Bats.