CC-1138, whose official nickname was Bacara, was a clone commando in the Grand Army of the Republic. He led his troops into battle fearlesly, often loosing thousands of soldiers in a single charge. This strategy led him to best many of the seperatists best generals.
He was promoted to lead the Galactic Marines. Bacara showed more care for his soldiers, and led massive suicide charges less often.
During Order 66, Bacara was assigned to kill Ki-Adi-Mundi while fighting the InterGalactic Banking Clan on Mygeeto. Mundi was surprised by Bacara's sudden betrayal and despite being able to block several shots, perished.