Forgotten History
Forgotten History is a Star Trek: Department of Temporal Investigations novel – the second book in the series – written by Christopher L. Bennett. Published by Pocket Books, it was first released in .

The novel is set partly in the Original Series era, and details the origins of the Department of Temporal Investigations in the 2260s and 2270s and its connection with the crew of the .

Summary 
From the book jacket
The agents of the Department of Temporal Investigations are assigned to look into an anomaly that has appeared deep in Federation territory. It's difficult to get clear readings, but a mysterious inactive vessel lies at the heart of the anomaly, one outfitted with some sort of temporal drive disrupting space-time and subspace. To the agents' shock, the ship bears a striking resemblance to a  starship, and its warp signature matches that of the original Federation starship Enterprise NCC-1701 – the ship of James T. Kirk, that infamous bogeyman of temporal investigators, whose record of violations is held up by DTI agents as a cautionary tale for Starfleet recklessness toward history. But the vessel's hull markings identify it as Timeship Two, belonging to none other than the DTI itself. At first, Agents Lucsly and Dulmur assume the ship is from some other timeline… but its quantum signature confirms that it came from their own past, despite the fact that the DTI never possessed such a timeship. While the anomaly is closely monitored, Lucsly and Dulmur must search for answers in the history of Kirk's Enterprise and its many encounters with time travel – a series of events with direct ties to the origins of the DTI itself…

Background information 
 The novel was announced by Bennett on . 
 This novel was later collected, along with the Pocket TOS novels The Rings of Time and That Which Divides, in the eBook omnibus Star Trek: The Original Series - The Continuing Missions, Volume 1.
 , which appeared to be an exact duplicate of Earth in composition in , is described as being an alternative version of Earth from a parallel universe which arrived in the primary universe as a result of a subspace confluence. It was eventually returned to its own universe by the same process in 2275, having been transposed with a Vedala planetoid from the same universe.
 The American cultural parallels of the Yangs on Omega IV are shown to be a result of cultural contamination, rather than parallel evolution: the flag and "sacred" documents had been left behind by a 2140s Earth Cargo Service freighter, hoping to inspire their fight against the Kohms.
 The exact dates to which the Enterprise traveled to in  and  are given as July 12, 1969 and April 4, 1968 respectively. The former is consistent with the fact that the scenes set in 1969 took place shortly before the launch of Apollo 11, which happened in real life on July 16 of that year. Furthermore, the latter is consistent with Spock's claim that an important assassination occurred on the date of their arrival according to the historical records. In reality, April 4, 1968 was the day that  was  in Memphis, Tennessee, only six days after the initial broadcast of "Assignment: Earth".
 According to the novel, the Guardian of Forever does not simply depict history but essentially reruns it at an accelerated rate. Grey's scans of  during the 2230s resulted in history being altered in , necessitating Spock's trip back in time to Vulcan in 2237 to save his younger self from a le-matya.
 The novel depicts the circumstances of Kirk's promotion to admiral as being both punishment and reward for his repeated violations of the Prime Directive, including a look at his last mission on the Enterprise. During this mission, Kirk provided a planet's native population with vital medical supplies to cope with an environmental catastrophe, despite their leaders' belief that the crisis was a test of their faith, as such a 'strategy' would have decimated the population; Kirk justified his decision by arguing that the medical supplies would be presented as having come from a now-destroyed settlement on another continent rather than another world. With Kirk's argument and the accompanying outcry of public support for Kirk's humanitarian actions, the tribunal are convinced to promote Kirk as a reward to the public and "punishment" in private as they recognized that Kirk would not enjoy a role in the admiralty.

Cover gallery

Characters 
Dulmur
Lucsly
James T. Kirk
Spock
Leonard McCoy
Montgomery Scott
Hikaru Sulu
Nyota Uhura
Pavel Chekov
Christine Chapel
Meijan Grey
Aleek-Om
Leslie
DeSalle
Gabler
Erickson

Hadley
Kyle
Willard Decker
DiFalco
Nogura
T'Pring

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Novels