A question for the legal eagles out there

With Charlie Rangel (D-NY) once again trying to bring back the draft (it is worth noting that the last time he did this, the Republicans pulled the low-down, dirty, unethical trick of putting his bill up for a vote exactly as he wrote it, leading to its defeat by a 402-2 vote, with Rangel himself voting against his own bill), one question keeps coming to mind:

How the dickens is compulsory military service allowable under the Constitution, especially the 13th Amendment, which states:

Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.

I’d have to say that “serve in the military or go to jail” seems to violate the spirit, if not the letter, of that amendment…

Watergate on the Merrimack?
Happy Thanksgiving