The Chiss-Imperial War Council was the Jedi Council that ruled during the time-period between the Swarm War and the Korriban Massacre. It was unable to prevent the Chiss-Imperial War from breaking out, but it successfully contained the war in the Unknown Regions, and stymied the Sith.
The Jedi Council following the Swarm War was in relative dis-favour with the Galactic Alliance and certainly with the Chiss Ascendancy following the conclusion of the Swarm War. Jedi and Galactic Alliance relations had hit an all time low, and the Jedi Council was responsible for the deaths of millions of Chiss soldiers at the Battle of Tenupe - as well thirty Chiss Star Destroyers and dozens of other warships. Though Luke Skywalker managed to repair a great deal of the damage done, distrust was in the air.
The Chiss suddenly grew more bold, and demanded that Jaina Solo and Zekk be expatriated to their space for trial into war crimes against the Chiss. The Jedi Council refused, and the GA was caught once again between the two. Determined to end the crisis, Cal Omas secretly made a deal with the Imperial Remnant to hand over to them Mygeeto and other worlds in exchange for pressuring the Chiss to accept a compromise.
That compromise, created with the agreement of the existing Jedi Council, was the creation of a new Council - with a new policy of appeasement towards the Chiss.
The Jedi Order was never particularly top heavy, and from the three hundred Jedi that existed, there were less than twenty Jedi Masters, and thus promotions were inevitable. The first difficult decision was in choosing a new Grandmaster, but eventually the Jedi agreed to accepting Daye Azur-Jamin as the Grandmaster. His recent brush with the dark side had matured Daye, turning him into a competent commander. Kirana Ti was placed on the Council with him, having been bypassed for Grandmaster simply because she wasn't interested. Streen came with her, as too did Waxarn Kel and Mandurrin, both elevated in rank due to their efforts during the Yuuzhan Vong War. Members of the Wild Knights took up roles, Wonetun and Izal Waz joining the Council. Klin-Fa Gi also joined up, and Tresk Im'nel offered the Council a strong GA voice. Dorsk 83, having proven himself during the war, was also offered a place.
With ten members, it was considered that the Council was sufficiently well-rounded. The old Council masters proceeded to head into retirement or other endeavours. Luke Skywalker and Mara Jade Skywalker settled down on Coruscant, while Kyle Katarn eloped with Jan Ors - although they never actually married while away. Clighal returned to Yavin 8, helping the underwater civilisation there recover from the Yuuzhan Vong war, and so the old Council generally severed ranks with the new.
It wasn't long until the Council was tested. The Chiss simply sealed their borders and began increased military maneuvers, surprising the Jedi and the GA. The Remnant pressed for the systems they had been promised secretly, but Cal Omas refused - the Moff Council had hardly secured the peace. Relations between the Remnant and GA ebbed, even with Pellaeon's efforts. His position as Supreme Commander of the Galactic Alliance had limited his position within the Remnant, and so the Moff Council was free to dominate the regime.
Chiss and Remnant relations took a nose-dive when the Moffs noticed that the Chiss were reactivating more Chiss Star Destroyers, vessels which the Moffs demanded. When the Chiss outright refused, the Moffs, knowing how damaged the Chiss were by Swarm War, dispatched warships to the Chiss border, enroaching on the Nirauan system.
The Chiss reinforced the world, and a steady arms race began to build-up in the next few days, the Chiss stubbornly refusing to negotiate with anyone, their new Queen completely throwing off the political balance. The Jedi asked for caution, and eventually convinced the GA to intercede, lending a Jedi task force to the 5th Fleet, commanded by Pellaeon and including the Megador, which deployed itself between the two fleets at Nirauan.
Treachery followed, and the Battle of Nirauan broke out between the three elements, triggering the Chiss-Imperial War. A group of Sith emerged on the side of the Chiss, and the Jedi suddenly realised the reason for Chiss obstinance - they knew the support they had. The Jedi rallied, dispatching teams of Jedi to Reecee, Adumar and Bilbringi, intending to contain the conflict. Other Jedi reinforced the praxeum on Dathomir, completing the Jedi net around the war.
The Sith were contained entirely, while the GA, Remnant and Chiss exchanged volleys over far-flung worlds such as Selvaris and Kalee, as well as Mygeeto. The action was limited, but it dragged on for two long years, costing the three factions. The GA could end the war in an instant, but was held back by the Jedi, determined to end the war without such an overpowering deployment. The public, on the other hand, saw war as the quickest way to resolve the issue, which was a worrying mentality - one the Council was too busy to deflect with the Chiss-Imperial War.
The Jedi Council met two years into the Chiss-Imperial War to debate the induction of a new student. This student brimmed with the Force, and suddenly revealed himself to be some kind of monster. Going by the name of 'Korriban', the creature proceeded to slaughter the Council, one and all, and then the Knight that rushed into the Council chambers thereafter.
The death of the short-lived Council was eventually recovered from. With the old Jedi Council active throughout the galaxy, and some even in partial retirement, the Jedi Order was crippled for the first few days of the Deity Crisis.