I was a big fan of C.L Bennet's Department of Temporal Investigations: Watching the Clock. It was a new kind of Star Trek novel, depicting a fascinating mixture of bureaucrats dealing with minutiae and an outsider's perspective on all the various time-travel shenanigans we saw through all of the recent series. In WTC, we didn't get much information on the Original Series but that seemed like a big undertaking with Captain Kirk's somewhat legendary relationship with time travel.
"Seventeen recorded violations!" as Agent Lucsly would say.
Forgotten History attempts to make up for this conspicuous absence by dealing with Captain Kirk's relationship with the DTI. As the first recorded time traveler in Federation history, his actions lead up to the founding of that body and their reactions to his further incursions into the time-stream. C.L Bennet is a master of incorporating obscure canon into his stories, including the largely forgotten animated series.
Fans of Watching the Clock may be disappointed that the previous stars of the book, including several minor characters from TNG who grew into fully-developed time agents, barely factor into this book. The work was written as a Star Trek: The Original Series novel and it shows.
I can't say this isn't disappointing on some level. I love Captain Kirk, Spock, and Scotty but I was hoping for more information about Lucsly and Dulmer. They have some good bits in this novel but I felt they were a bit stereotypical in places. Lucsly, for example, has a passionate hatred of Captain Kirk which seems disproportionate given what we know of both men. Even if he viewed Kirk as a menace to linear history, he had to also know he spent a substantial amount of time patching up the timeline too.
I will say, however, the book does something clever with time travel. A minor theme of the book is that the way we remember history isn't remotely how it happened. History is a story, which is obvious if you think about it, meant to tell us about what we can achieve or should avoid as much as what happened.
Characters from the future discovering people from the past aren't all sunshine and roses or Sauron wannabes adds an interesting perspective to the book. I will say, however, there's a bit at the end which really annoys me. A Starfleet officer's first obligation is to the truth so a character should never deny the "warts and all" of the past as well as the reverse. I think knowing George Washington had slaves, for example, doesn't diminish his accomplishments while also warns us away from making his mistakes.
The original series characters work extremely well and I particularly liked the handling of Spock. The "arc welding" of various Trek series is quite cool with Spock having some pointed opinions on the Vulcans of T'Pol's time. There's a subplot I won't spoil but harkens back to my favorite Spock episode too, with an unexpected guest star.
In conclusion, this is a really good book. One I am very glad to have bought and one of my favorite Star Trek stories. Unfortunately, I really wish we'd seen more of the Temporal Agents. They were guest-stars and it would have been nice to see a character do a complete 180 on his opinions. That would have made the book a perfect 10.