The Book of the War

 was an encyclopedia-style primer for the War, published 50 years into the conflict. Its authors and audience are never made explicit, but there are hints that it was written by brainwashed agents of the Great Houses for a human or posthuman audience. (PROSE: The Book of the War)

Reliability
The enemy apparently retro-erased several entries that contained compromising information. These were Churchill Index, Immaculata Formosii, the Gods of the Ainu, "Miss Hiroshima", Mohandassa, Sixth Wave Defections, S'tanim, and Violent Unknown Events. (PROSE: The Book of the War)

The book claimed that culturally-human artificial intelligences were not resurrected in the City, when actually, as part of the Universal Machine, they were. (PROSE: The Book of the War, Of the City of the Saved...)

The Shift rewrote the reader's perception of the book multiple times to explain its own life story. The entry on "You" Diversions arguably housed an example of its subject. (PROSE: The Book of the War)

Behind the scenes
The Book of the War was the fictional book-within-a-book contained in the Faction Paradox novel of the same name.