The first group of size one documents in the Ethan A. Jenks collection primarily contains Civil War correspondence related to the Seventh Regiment, Rhode Island Volunteers. This group begins with Jenks' enlistment as Recruiting Officer (#2), and contains letters pertaining to Jenks' service as Captain, reflecting his responsibility to provide descriptive lists and monthly returns (#4, 10, 11, 18, 26). One item serves as a detailed sketch of a battle plan for an unspecified location (#29), revealing strategic positioning of troops and precise notation of distance. Following the 17 November 1862 Battle of Fredericksburg, Jenks wrote to his wife Sanondess (#6), stating "O my God I never want to witness another day like that yet I come out unharmed." Along with #30, written to Sanondess in 1865, Jenks' description of Fredericksburg offers a compelling personal description of the Civil War.

Group two of size one documents in the Jenks collection contains post-War correspondence pertaining to Jenks' service as commander of the Seventh Regiment. This group includes Colonel Zenas Randall Bliss' decline to attend an 1893 annual meeting of the Seventh Rhode Island Veterans Association. Group two also contains Jenks' correspondence with William Palmer Hopkins concerning Hopkins' book, The Seventh Regiment Rhode Island Volunteers in the Civil War.

Documents in group three reveal the complete story of Jenks' discharge and reinstatement, an unexpected misunderstanding which plagued the Captain with years of legal skirmishes. While on the battlefield at Vicksburg, Mississippi, in July 1863, Jenks was informed of his discharge, which had officially occurred on 4 May due to his failure to appear before a military commission of which he had no previous knowledge. The commission was called because Jenks had enlisted Private James Briggs, who was found physically unfit after only one month's service (refer to #68 and 69 for Jenks' own statements). Jenks' case was heard promptly, his statements supported by the recommendation of Colonel Bliss (#47) and Rhode Island Governor James Y. Smith (#54), and he was restored to command by special order 12 August 1863. However, Jenks fought an extended legal battle attempting to claim pay for the period between his discharge and reinstatement, (#64-67).

Groups four through twelve include various military documents primarily relating to the Seventh Regiment, Rhode Island Volunteers, such as monthly returns of clothing, camp, and garrison equipage (#72-87), military invoices (#88-108), clothing receipt rolls (#109-111), general and special orders (#112-132), hospital records (#133-176), military notifications (#177-188), miscellaneous military documents (#189-216), ordnance records (#217-260), military receipts (#261-272), and documents related to pension claims (#273-280).

In the 1880s and 90s, Jenks served as a Rhode Island deputy tax collector. His service as such is reflected by group fourteen (#281-308), primarily containing correspondence between Jenks and district collector John I. Hutchinson. Miscellaneous documents in group fifteen include Jenks' service as assignee of Paine & Colwell property, including a store complete with goods and merchandise (#312-318). Fifteen also includes evidence that following Jenks' death, Sanondess purchased a tract of property known as the Tobey farm in Johnston, Rhode Island (#322-328). The remainder of size one documents include miscellaneous photographs circa 1861-1916 (#329-340) and envelopes/postage receipts which possibly correspond to documents within the collection (#341-394).

Size two (#395-431), size three (#432-466), and flat files (#467-475) contain military records such as those found in groups four through twelve. Size two bound manuscripts (#476, 477) contain morning reports 1862-1865, and object (#478), a pocketbook, is shelved for re-housing.