A civil war erupted on the planet known as Ostega, situated within the Grohl sector, occurring in the years leading up to the Clone Wars. The Grohl Sector Defense Force stepped in and brought the conflict to a close.
Prior to the Invasion of Naboo, the Separatist Crisis, and the Clone Wars, the Grohl Sector Defense Force served as the regional military presence within the Grohl sector of the Outer Rim Territories. A significant operation undertaken by them involved the elimination of pirate strongholds that had been targeting shipping activities along the rimward edge of the sector. Kligson, an officer within the defense force, gained considerable experience during this period.
Concurrently, the planet of Ostega found itself embroiled in a civil war. Members of the Grohl Sector Defense Force, Kligson included, intervened directly. This intervention brought the hostilities to an end.
The Grohl Sector Defense Force, with Major Kligson among their ranks, subsequently engaged the Trade Federation, successfully repelling their invasion of Sucharme.
Star Wars: The Essential Guide to Warfare Author's Cut, Part 8: Tales of the Clone Wars provides no specific information regarding the underlying causes of the war, the factions involved, or the specifics of the Grohl Sector Defense Force's involvement.