Actually, most people seem to forget that a volunteer, mostly foreign-born military has been the historical norm for the United States, not a recent development. There was a time when military service was considered a sort of pre-requisite for a political career (hence the Kennedys and others serving), but that was mainly in the officer corps. I'd say that was a direct outgrowth of the Civil War and the surplus of men who held general ranks in the various Volunteer forces...we saw the same thing during the Spanish-American War and its aftermath and before that with Mexico.

The wars that used citizen-soldiers (draftees) were for the most part full-scale conflicts (the Civil War, World War I, and World War II...there were draftees in Korea and Vietnam, but the creation of a "Vietnam-only" draftee force did more than anything else to end the draft). They had uneven records for the most part in the early stages of each conflict (Vietnam being the only exception).