The Chronicles of War was an archival database that contained the various campaigns, missions and battles conducted by the Klingon Empire. It was archived by the Klingon High Council who were known to withhold certain events in order to suit its own purposes.
In 2293, Kahnrah took his granddaughter K'ahlynn to the Museum of Military Triumph and Conquest in order to meet the Overseer Morglar so that he could detail a mission where he served under Captain Kang. At the time, he along the rest of the crew battled the personnel of the USS Enterprise under the influence of the (*) entity. However, it was only the actions of Captain James T. Kirk that allowed the Klingon crew to survive. This led to the record not being archived in the Chronicles of War as it would paint a different picture of the Humans of the Federation. (TOS comic: "Blood Reign O'er Me")