Historically the first conscription in modern times was done by the French:

"Conscription in its modern form arose in revolutionary France, where universal military service was regarded both as a Republican duty, based on the principles of equality and fraternity, and as a necessity for national survival. In August 1793, a law limited liability for service to men between the ages of 18 and 25" (source)

In those times most people did not go to high school or the local equivalents.