Yos Kolina was the king of the Mon Calamari system and the father of the young Prince Lee-Char. At the start of the Mission to Iceberg Three, he contacted the Jedi telling them that if they didn't assist the planet soon, he would not be able to prevent conflict in the region. Shortly after the campaign was over, Plo Koon reported that he was assassinated, and as a result, Mon Calamari was on the brink of a civil war.
Mission to Iceberg Three takes place right after the Season 3 finale episode (of the Clone Wars television series) Wookiee Hunt and right before the Season 4 starting episode Water War. Yos Kolina was killed for Water War, Gungan Attack, and Prisoners to make sense of Lee-Char to be king, and the riot of the Quarren did begin after the Separatist invasion.