There were 2 prior instances of a nationwide drafts.
First one was during the Civil War in 1863 though if one includes the Confederate side, they implemented theirs a year earlier in 1862.
Second one was in 1917 in preparation for the US entry into WWI.
In both instances, there was strong opposition either due to negative effects on those affected and/or because some opponents felt it was contrary to their interpretation of American ideals and a gross infringement of individual rights by the state.
Especially during the Civil War. From those on the Confederate side as they felt it was a form of slavery to the state and thus, contrary to their interpretation of Confederate states rights ideals. Some governors like Georgia’s Joseph E. Brown went so far as to liberally issue critical civil service worker exemptions to men affected by the Confederate draft in order to resist what he considered an usurpation of state prerogatives.
On the Union side, you had anti-war protests, attempts by the Confederate sympathizing Copperheads to undermine the Union cause, and even the infamous 1863 draft riots in NYC which lasted 3 days, caused the deaths of many African-Americans and Abolitionists, and necessitated the use of military force…including Naval gunfire to put down.
Fitness standards have been raised and lowered in history depending on how pressing manpower needs were.
Incidentally, during WWII, ~25% of all draftees called up were declared unfit for service due to medical conditions/stunted growth related to malnutrition due to regional poverty/The Great Depression. This was one of the key factors in the implementation of publicly funded free/reduced school meals program in public K-12 schools after the war.