Population Advantage of the North
The north handily had an advantage in population. Due to the influx of immigrants and runaway slaves, as well as the centralized cities and dense populations of the north, the Union army was able to recruit much more men to fight. Many of the Union generals took this advantage into account when they were planning attacks and strategies. As shown by the graph above, the north had over 100,000 more casualties and nearly 1,000,000 more that served in a Union uniform. Many battles, for example, Gettysburg, exemplified the intentions of the generals of the north. Although they became victorious when the firings ceased, the amount Union soldiers dead amounted to significantly higher numbers than those of the Confederacy.
The Civil War was as bloody as any war America has ever witnessed. This was mainly due to the fact it was American vs. American. Casualties ranged into the 600,000's. This devastated American families as well as the country itself. With the recruitment of soldiers being more localized, soldiers constantly fought alongside many people they new in their community. So when company A of the 11th Mississippi was completely wiped out, it brought about a difficult toll onto the families of that area. It also brought about an increase in social power and responsibility for women, due to the amount of men missing from family lives in some instances.
http://www.civilwar.org/education/civil-war-casualties.html