Frequently, the history of the American Civil War is painted with scenes of the battlefield, images of Thomas “Stonewall” Jackson's efforts at Chancellorsville or of the 20th Maine's defense at Gettysburg. Stories are told of the deaths and casualties suffered on the battlefield and the horrors of such battles of Antietam. While recounting the strategies of the battlefield offers military historians a glimpse into the mind of the commander in the field, little is usually discussed regarding the timing of battle. Andrew M. Bell offers a rarely discussed insight into the timing and outcomes of key battles by examining an often overlooked enemy during the American Civil War: disease transmitted by mosquito.

Very quickly Bell reveals that of the 620,000 soldiers to die during the American Civil War, over two-thirds were not taken directly by gunshot wounds or cannon, but by disease (pp. 1–2). While accurate statistics are available only for Union troops, it is quite plausible that Confederate troops suffered far worse than their Union foes due to inadequate supplies of crucial medication.

Bell shows, using a collection of personal correspondence and Union Hospital Records, that a substantial fraction of the deaths and illnesses contracted during the war were due to the mosquito. Various breeds of the mosquito transmitted two of the most annoying and feared maladies of the war: malaria and yellow fever. While malaria is rarely fatal on its own account, it interacted with other diseases such as typhoid and dysentery to make a soldier's life miserable, often leading droves of soldiers to become unfit for duty. Yellow fever or “Yellow Jack” was significantly more deadly, and was often diagnosed only after the patient ejected black vomit caused by blood pooling in the stomach.

While yellow fever occurred at a low frequency, its deadly effects for those never exposed caused a panic. The fear of a yellow fever outbreak directly influenced military strategy at Galveston in 1862. William Renshaw, who led the attack against Galveston, allowed the escape of Confederates and firepower stating, “‘two old-fashioned 24-pounders, one 80-pounder, and another gun’ were not worth the price of exposing his sailors to a 'fatal disease’ that promised to kill 'many innocent people’” (p. 40).

Both yellow fever and malaria gave the Confederates what they believed was some wiggle room during the summer and fall months. General Lee routinely moved troops away from malarious regions during the summer months to aid against impending attack. As General George McClelland moved troops towards Richmond, General Lee wrote to John Pemberton, “At this season I think it impossible for the enemy to make any expedition into the interior” and “The troops that you retain there [South Carolina] will suffer more from disease than the enemy” (p. 68).

Eventually, in order to mount a successful campaign against the Confederates, the Union troops would have to mount an attack during the sickly season. General Grant made a bold move by advancing south of Vicksburg, the final stronghold of the Mississippi River during the summer of 1863. Union troops were occupying territory near major mosquito breeding grounds, the Yazoo River, the Bick Black River, and various parts of the Mississippi River. The close proximity to mosquito breeding grounds led to at least 17 percent of Grant's troops to be infected with malaria (p. 78).

While many of Grant's troops suffered with fever and chills, they had the benefit of ample quinine supplies. Quinine was the only known treatment for malaria's affects. Confederate soldiers who were trapped by the siege of Vicksburg were not as lucky. The supplies of quinine in Vicksburg were used quickly, leading to increased illness amongst the troops. It was reported that over 50 percent of the Confederate troops in Vicksburg were ill. Rather than see his frail troops mount an ill-conceived attack, General Pemberton surrendered the city to Grant.

Other authors have noted in passing that disease played a role in the outcomes of the war, particularly in the vicinity of Vicksburg during prior campaigns to capture the city.Footnote ¹ Others have also mentioned the relationship between the battlefield and the increased incidence of disease in communities near military encampments or field hospitals.Footnote ² While disease is constant of war, Bell is one of the first to shed insight into the fact that disease patterns matter. Throughout the book, Bell uses handpicked examples to show how disease played a role in shaping the strategy of the generals in the field or how it affected the outcomes once the strategy was implemented. Whether fear prevented marines from going ashore in fear of yellow fever, or troop strength dwindled because of ague, disease played a significant role in the outcome of the war.

While the book offers multiple examples of malaria and yellow fever playing out it is difficult to follow the timing of events and how interconnected they are. Furthermore, it is unclear in some settings what the increase in population adjusted malaria rate is in a given theatre of war. In some of these areas where infection rates are reported to be 17–25 percent of troop strength, the troop infection rates may mirror the infection rates of the local population. Perhaps by comparing rates in locations to the 1880 Census records, the reader could get a sense of how the close quarters of the troops led to the spread of disease.

For those interested in Civil War history or the spread of infectious disease, this book shows how the two interact.