Cucuruz Doan was a mobile suit pilot for the Principality of Zeon, piloting a MS-06J Zaku II Ground Type. During one battle, his gun misfired, resulting in the death of several civilians. Doan was then ordered to kill the children of the civilians he had accidently killed. But Doan could not bring himself do it, and deserted the army, taking the children with him. He established residence on an island in the Pacific, swearing an oath to himself to protect them.
(Source: Gundam wiki)
