The Second Battle of the Land of Light in Nebula M78 was a brief conflict between Belial and the Space Garrison. See Mega Monster Battle: Ultra Galaxy Legends The Movie.
Cause of Conflict
The cause of the conflict was Belial's release from the Space Prison by a rogue Alien Zarab, who Belial killed prior to the actual conflict. The alien freed Belial with his Giga Battle Nizer, setting off the Prison's alarms and calling the Space Garrison beginning the conflict.
End of Conflict
The conflict ended after Belial made his way through the Space Garrison to the Plasma Tower and took the Plasma Spark from its resting place. Escaping with it, Belial left his homeworld frozen and a majority of the Ultras sealed away in thick ice.
Later on, the act was undone, by Ultraman Zero, who returned what Belial had stolen, restoring the planet and its people.