Challia Bull was a Zeon officer originally stationed in the Jupiter sphere, but was later summoned back to the Earth Sphere by Gihren Zabi in the late stages of the One Year War, who believed Bull's Newtype powers could be of great help for Zeon's campaign.
Bull was sent to Granada and placed under Kycilia Zabi's command. Upon his arrival, Kycilia directed Bull to pilot the MAN-03 Braw Bro with Simus Al Bakharov, though told him that if he displayed more Newtype potential than Lalah Sune, he may take over as pilot of the MAN-08 Elmeth. Bull and Simus then went to provide support to Char Aznable's Zanzibar.
Bull and Simus later takes the Braw Bro out in order to test it. He soon encounters the RX-78-2 Gundam and attacks it. However, the Gundam's technology outclassed the Braw Bro and Bull was killed in the Braw Bro's destruction alongside Simus.
Principality of Zeon