Final answer:
The Enrollment Act, passed by Congress in 1863, mandated that certain age groups of Union male citizens and immigrants register for military service and were subjected to a draft via a lottery system, although exemptions could be purchased.
Step-by-step explanation:
The Enrollment Act of 1863
The Enrollment Act, passed by Congress in March 1863, was a critical piece of legislation during the Civil War that required Union male citizens and immigrants who had filed for citizenship, between certain ages, to register for military service. Specifically, it required all unmarried men between the ages of twenty and twenty-five, and all married men between the ages of thirty-five and forty-five, to register. Those who registered were eligible for the draft, with a lottery system used to select draftees. While there were no exemptions by occupation, wealthy individuals could avoid service either by hiring substitutes or paying a commutation fee of $300 to the federal government. This act was an early form of conscription in the United States, aiming to bolster the Union army as volunteer enlistments declined.