The diary housed in this collection constitutes John M. Hollis's personal account of the Civil War and documents his service with the 38th Illinois Infantry Regiment in Arkansas, Missouri, Mississippi, Alabama, Kentucky, and Tennessee. Much of the diary is devoted to descriptions of the unit's surroundings and the day's march, but Hollis also provides descriptions of two major battles. The first of these battles began at Perryville, Kentucky on 1862 October 8 and was the largest battle fought in that state during the Civil War. Hollis notes that the Union Army captured 90 prisoners and describes the burying of the dead following the battle.

The next major fighting that Hollis describes began at Murfreesboro, Tennessee on 1862 December 31. Hollis depicts the beginning of the battle as being like a stampede. He mentions the strength of the Confederate line and notes that they did not gain much ground in the initial push. He is optimistic on January 1: "Still the fight continues though not so terable as the day before our men holds there position with great effort." The fighting died down by January 4th, but Hollis's unit remained in Murfreesboro for some time after.