More than 2,000,000 Federal soldiers were twenty-one or under (of a total of some 2,700,000)-
More than 1,000,000 were eighteen or under.
About 800,000 were seventeen or under.
About 200,000 were sixteen or under.
About 100,000 were fifteen or under.
Three hundred were thirteen or under-most of these fifers or drummers, but regularly enrolled, and sometimes fighters.
Twenty-five were ten or under.
This website shows the number of soldiers and their ages when they join either the confederate or union armies as shown above