Sung is a man of extremes. Sung believes that there is no chance of defeat when the battle is going well, but the minute the tide begins to turn, he loses all hope of victory and panics. Sung only recently became a general and is not very competent, as displayed when he came near to succumbing to a nervous breakdown after the Terra Team had been defeated.
Sung originally refused Aang's help in stopping the Drill that the Fire Nation was using to attack the outer wall, believing he could handle the situation himself, but humbly requested the Avatar's assistance after the Terra Team, an elite team of Earthbenders, were defeated by Ty Lee and failed to destroy the machine.
It is likely that General Sung and the rest of the Council were freed after the War ended.