Only about 5-6% of the Union armies were composed of draftees or substitutes. Some states were not subject to the draft because they had an excess of volunteers.
In the 1863 draft (by far the largest), of all the names drawn, 30% were found to be ineligible "on account of physical disability." Another 30% were found to be exempt for some other reason ("alienage, unsuitableness of age, non-residents, &c"). Of the remaining 40% "held to service," about half paid the $300 commutation; of the half remaining, "about one third have gone in person, and two-thirds have furnished substitutes."
In October 1863, Provost-Marshall General James B.Fry sent to Secretary Stanton the following interesting analysis of the first round of Federal conscription:
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