The Venue Accords were the only attempted peace treaty in the War in Heaven. They occurred in the War's 5th year. Representatives of the Great Houses, their enemy, and the Remote attended negotiations over the Accords, but Faction Paradox was not invited due to it being in a weakened state at the time. The actual negotiations lasted less than a picosecond and concluded that peace was an impossibility.
Negotiations over the Accords occurred in a sentient space-time event the size of a small galaxy. (PROSE: The Book of the War)