This addendum contains five letters and a leather-bound notebook. The letters were either written by or sent to Hughes; one of the letters is dated from 1860, two from 1861, one from 1863, and one is undated (box 1, folder 11). The notebook was kept by Hughes between the years of 1857 and 1861 (box 1, folder 12). (1857-1863, undated; 5 letters consisting of 7 leaves and 13 pages, 1 notebook)

The letter of 5 October 1860 was written by David Hibbs and addressed to a "Dear friend", presumably Hughes. Hibbs offers news of family members and mutual acquaintances. He also discusses visiting Hughes for a hunt, but is concerned about the dangers and expense of traveling.

The letter of 20 April 1861 consists of two parts. The first part is likely a draft of an unsent letter from Hughes to President Lincoln regarding Hughes' concern about the number of secessionists in (West) Virginia and the threat that they pose to the Union, as well as the need for Unionists to arm and organize. The second part is a separate letter written on the same leaf of paper, in blue ink rather than the usual black. This letter is signed "a girl in trouble" and has no salutation. This letter appears to have been written by a young woman engaged to a young man that she no longer loves and wishes for the recipient, presumably Hughes, to aid her in breaking the engagement. There is also a photocopy of these two letters.

The letter of 25 December 1861, written by Hughes from Camp Leedsville in Randolph County, is addressed to Dr. A. Brown. Hughes describes the hardships of the soldiering lifestyle, but also his determination. He describes the Battle of Greenbrier River (3 October 1861) in detail and also makes reference to the Battle of Allegheny Mountain (13 December 1861), as well as other conflicts with Confederate troops and secessionist sympathizers. Hughes takes a hardline stance against all rebels, describing his habit of killing such men where he finds them. He writes that there are no Confederate troops currently on his side of the mountains and he predicts that the fighting will soon be finished, at least in (West) Virginia. Hughes mentions the possibility that Britain might enter the war on the side of the South; such speculation is likely a consequence of the Trent Affair having occurred the previous month.

The letter of 1 June 1863 was written to Hughes by his mother. She expresses concern for the Hughes and is particularly worried because she has not received any letter from him recently. She also provides news from home about Hughes' father, friends, and other acquaintances.

There is also an undated letter fragment signed by Hughes which appears to be the final pages of a longer letter. Hughes writes from Fort Kasper in the Dakota Territory and gives his rank as Sergeant. The letter regards Hughes' opinions regarding the local Indians, namely that they cannot be civilized and should be exterminated so that American settlers and miners can make better use of their land. Hughes asks for news from the States and writes that he has heard little of goings on back east "since the war closed".

The leather-bound notebook contains financial accounts, measurements, and technical sketches (1857-1860); and notes regarding Hughes' military service (1861).