This collection consists of 44 letters from John M. Jackson to his family during the Civil War. With one exception, the letters in this group were addressed to members of Jackson's immediate family — most commonly, to his mother or sisters. The four earliest (September and October 1862) were written from Camp Abraham Lincoln in Portland, Maine, where the 23rd Maine was organized. There follow 12 letters (11 dated from October 1862 to April 1863, and one without date) written from the Potomac defenses. Most of these originated from Camp Grover, Maryland (some 15 miles northwest of Washington) or from Edwards Ferry (about 30 miles northwest). The remainder of Jackson's service in the 23rd Maine is unchronicled — as are his months as a civilian (with the exception of a single letter dated 15 November 1863) and the period of his enlistment in the 32nd. When the letters resume Jackson is already in Virginia, caught up in Grant's colossal offensive. Three letters were written on the Overland campaign, from the battlefields of Spotsylvania (14 May 1864), North Anna, (25 May) and Cold Harbor (5 June). There follow eight letters (25 June to 13 August 1864) from the trenches outside Petersburg. From the period of Jackson's illness (August to December 1864), there are three letters from the 2nd Division hospital near Petersburg, followed by five from the 9th Corps hospital at City Point, Virginia and five from St Paul's Church Hospital at Alexandria. The two final letters in the group were written as Jackson returned to his regiment, before consolidation.