Final answer:
About 1,000,000 men fought for the Confederacy and 2,000,000 men for the Union during the American Civil War, a conflict that resulted in significant loss of life from battle and disease.
Step-by-step explanation:
During the American Civil War from 1861 to 1865, approximately 1,000,000 men fought for the Confederacy, and about 2,000,000 men fought for the Union. These numbers indicate the vast scale of this conflict, which was punctuated by significant battles such as the First Battle of Bull Run, where 30,000 Confederates faced 20,000 Union soldiers, ending in a Confederate victory.
The Union's call for 75,000 men after the surrender of Fort Sumter was met with an overwhelming response, and as the war continued, significant numbers of men enlisted or were conscripted on both sides, leading to the aforementioned figures of soldiers who served in each army by the war's end.
The death toll of the war was devastating, with about 220,000 military men killed or died of wounds, and about 400,000 dying from infectious diseases, reflecting the extreme human costs of this tragic chapter in American history.