Although my great-great grandfather Edward Willis was an illiterate Union private from Kentucky, he performed one of the most important jobs in an army: driving a commissary wagon.

Although it may have seemed like an inglorious job, the duty entailed at least three distinct perks. First, it allowed Edward, or any footsore infantryman, to sit rather than walk. Second, it put him in proximity to the food when it came to mealtime, always the brightest part of a soldier’s day. Finally, Edward now could count himself as among the Army’s most invaluable troops.

Providing sustenance to tens of thousands of men was a staggering task. Napoleon believed that “an army marches on its stomach,” and it may have been equally true that the success of both the Union and Confederate war efforts rested squarely on the shoulders of each Army’s respective commissary department. As Americans recover from the gluttonous feast that has become Thanksgiving, we should take a moment to consider the role food played in the drama of the Civil War.

The Union Army’s institutional structure for feeding itself reflected the best and worst of 19th-century military bureaucracy. While the Quartermaster Department tended to matters of transportation, clothing and ammunition, a separate department, the Commissary, focused almost exclusively on the procurement and distribution of “subsistence”: food and other daily necessities, like soap and candles....