The following map displays the monthly rates of malarial disease in the Federal armies and departments operating in the Atlantic Region from 1862-1866. This data is taken from Table XXVIII of Charles Smart's Medical and Surgical History of the War of the Rebellion. (Smart, 89-91) The Federal armies and departments included in this analysis of the Atlantic Region are the Middle Department, the Department of the Shenandoah, the Army of the Potomac, the Department of the Rappahannock, the Department of Virginia, the Department of North Carolina, the Department of the South, the Department of the East, the Department of Washington, and the Middle Division. (Smart, 19,98) From the map, it can be concluded that the rates of malarial disease in the Union Army increased in the summer months and as the War progressed.