author
Best known for helping document California’s military history, this little-known writer is credited as one of the authors behind a detailed 1895 account of Company B of the First Regiment Infantry during the Sacramento campaign of 1894.

by California. Infantry. First Regiment. Company B, Irving B. Cook, George Filmer, W. J. Hayes, A. McCulloch, William D. O'Brien
Very little biographical information about Irving B. Cook appears to be readily available in major public sources. He is listed by Project Gutenberg as an author connected with The "City Guard": A History of Company "B" First Regiment Infantry, N. G. C. During the Sacremento Campaign, July 3 to 26, 1894.
That book was originally published in 1895 and focuses on Company B, known as the "City Guard," along with the Sacramento campaign of 1894. Cook is named alongside George Filmer, W. J. Hayes, A. McCulloch, and William D. O'Brien, suggesting he contributed to a collaborative record of the unit's history rather than a large standalone body of literary work.
Because reliable biographical details beyond that publication are hard to confirm, the safest picture is of a late 19th-century writer or compiler associated with preserving a specific piece of California National Guard history.